Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to a Marine Geophysical Survey in the Northeast Pacific Ocean

DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XR074]

Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to a Marine Geophysical Survey in the Northeast Pacific Ocean

AGENCY:

National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce.

ACTION:

Notice; proposed incidental harassment authorization; request for comments on proposed authorization and possible renewal.

SUMMARY:

NMFS has received a request from the Lamont-Doherty Earth Observatory of Columbia University (L-DEO) for authorization to take marine mammals incidental to a marine geophysical survey in the northeast Pacific Ocean. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to issue an incidental harassment authorization (IHA) to incidentally take marine mammals during the specified activities. NMFS is also requesting comments on a possible one-year renewal that could be issued under certain circumstances and if all requirements are met, as described in

Request for Public Comments

at the end of this notice. NMFS will consider public comments prior to making any final decision on the issuance of the requested MMPA authorizations and agency responses will be summarized in the final notice of our decision.

DATES:

Comments and information must be received no later than May 7, 2020.

ADDRESSES:

Comments should be addressed to Jolie Harrison, Chief, Permits and Conservation Division, Office of Protected Resources, National Marine Fisheries Service. Physical comments should be sent to 1315 East-West Highway, Silver Spring, MD 20910 and electronic comments should be sent to

ITP.Fowler@noaa.gov.

Instructions:

NMFS is not responsible for comments sent by any other method, to any other address or individual, or received after the end of the comment period. Comments received electronically, including all attachments, must not exceed a 25-megabyte file size. Attachments to electronic comments will be accepted in Microsoft Word or Excel or Adobe PDF file formats only. All comments received are a part of the public record and will generally be posted online at

https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act

without change. All personal identifying information (

e.g.,

name, address) voluntarily submitted by the commenter may be publicly accessible. Do not submit confidential business information or otherwise sensitive or protected information.

FOR FURTHER INFORMATION CONTACT:

Amy Fowler, Office of Protected Resources, NMFS, (301) 427-8401. Electronic copies of the application and supporting documents, as well as a list of the references cited in this document, may be obtained online at:

https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act.

In case of problems accessing these documents, please call the contact listed above.

SUPPLEMENTARY INFORMATION:

Background

The MMPA prohibits the “take” of marine mammals, with certain exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361

et seq.

) direct the Secretary of Commerce (as delegated to NMFS) to allow, upon request, the incidental, but not intentional, taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region if certain findings are made and either regulations are issued or, if the taking is limited to harassment, a notice of a proposed incidental take authorization may be provided to the public for review.

Authorization for incidental takings shall be granted if NMFS finds that the taking will have a negligible impact on the species or stock(s) and will not have an unmitigable adverse impact on the availability of the species or stock(s) for taking for subsistence uses (where relevant). Further, NMFS must prescribe the permissible methods of taking and other “means of effecting the least practicable adverse impact” on the affected species or stocks and their habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance, and on the availability of the species or stocks for taking for certain subsistence uses (referred to in shorthand as “mitigation”); and requirements pertaining to the mitigation, monitoring and reporting of the takings are set forth.

National Environmental Policy Act

To comply with the National Environmental Policy Act of 1969 (NEPA; 42 U.S.C. 4321

et seq.

) and NOAA Administrative Order (NAO) 216-6A, NMFS must review our proposed action (

i.e.,

the issuance of an incidental harassment authorization) with respect to potential impacts on the human environment.

Accordingly, NMFS plans to adopt the National Science Foundation's (NSF's) Environmental Assessment (EA), as we have preliminarily determined that it includes adequate information analyzing the effects on the human environment of issuing the IHA. NSF's EA is available at

https://www.nsf.gov/geo/oce/envcomp/.

We will review all comments submitted in response to this notice prior to concluding our NEPA process or making a final decision on the IHA request.

Summary of Request

On November 8, 2019, NMFS received a request from L-DEO for an IHA to take marine mammals incidental to a marine geophysical survey of the Cascadia Subduction Zone off the coasts of Washington, Oregon, and British Columbia, Canada. The application was deemed adequate and complete on March 6, 2020. L-DEO's request is for take of small numbers of 31 species of marine mammals by Level A and Level B harassment. Neither L-DEO nor NMFS expects serious injury or mortality to result from this activity and, therefore, an IHA is appropriate.

NMFS has previously issued IHAs to L-DEO for similar surveys in the northeast Pacific (

e.g.,

84 FR 35073, July 22, 2019; 77 FR 41755, July 16, 2012). L-DEO complied with all the requirements (

e.g.,

mitigation, monitoring, and reporting) of the previous IHAs and information regarding their monitoring results may be found in the

Description of Marine Mammals in the Area of Specified Activities

section.

Description of Proposed Activity

Overview

Researchers from L-DEO, Woods Hole Oceanographic Institution (WHOI), and the University of Texas at Austin Institute of Geophysics (UTIG), with funding from the NSF, and in collaboration with researchers from Dalhousie University and Simon Fraser University (SFU) propose to conduct a high-energy seismic survey from the Research Vessel (R/V)

Marcus G Langseth

(

Langseth

) in the northeast Pacific Ocean beginning in June 2020. The seismic survey would be conducted at the Cascadia Subduction Zone off the coasts of Oregon, Washington, and

British Columbia, Canada. The proposed two-dimensional (2-D) seismic survey would occur within the Exclusive Economic Zones (EEZs) of Canada and the United States, including U.S. state waters and Canadian territorial waters. The survey would use a 36-airgun towed array with a total discharge volume of ~6,600 cubic inches (in

3

) as an acoustic source, acquiring return signals using both a towed streamer as well ocean bottom seismometers (OBSs) and ocean bottom nodes (OBNs).

The proposed study would use 2-D seismic surveying and OBSs and OBNs to investigate the Cascadia Subduction Zone and provide data necessary to illuminate the depth, geometry, and physical properties of the seismogenic portion and updip extent of the megathrust zone between the subducting Juan de Fuca plate and the overlying accretionary wedge/North American plate. These data would provide essential constraints for earthquake and tsunami hazard assessment in this heavily populated region of the Pacific Northwest. The primary objectives of the survey proposed by researchers from L-DEO, WHOI, and UTIG is to characterize: (1) The deformation and topography of the incoming plate; (2) the depth, topography, and reflectivity of the megathrust; (3) sediment properties and amount of sediment subduction; and (4) the structure and evolution of the accretionary wedge, including geometry and reflectivity of fault networks, and how these properties vary along strike, spanning the full length of the margin and down dip across what may be the full width of the Cascadia Subduction Zone.

Dates and Duration

The proposed survey is expected to last for 40 days, with 37 days of seismic operations, 2 days of equipment deployment, and 1 day of transit. R/V

Langseth

would likely leave out of and return to port in Astoria, Oregon, during June-July 2020.

Specific Geographic Region

The proposed survey would occur within ~42-51° N, ~124-130° W. Representative survey tracklines are shown in Figure 1. Some deviation in actual track lines, including the order of survey operations, could be necessary for reasons such as science drivers, poor data quality, inclement weather, or mechanical issues with the research vessel and/or equipment. The survey is proposed to occur within the EEZs of the United States and Canada, as well as in U.S. state waters and Canadian territorial waters, ranging in depth 60-4400 meters (m). A maximum of 6,890 km of transect lines would be surveyed. Most of the survey (63.2 percent) would occur in deep water (>1,000 m), 26.4 percent would occur in intermediate water (100-1,000 m deep), and 10.4 percent would take place in shallow water <100 m deep. Approximately 4 percent of the transect lines (295 km) would be undertaken in Canadian territorial waters (from 0-12 nautical miles (22.2 km) from shore), with most effort in intermediate waters. NMFS cannot authorize the incidental take of marine mammals in the territorial seas of foreign nations, as the MMPA does not apply in those waters. However, NMFS has still calculated the level of incidental take in the entire activity area (including Canadian territorial waters) as part of the analysis supporting our preliminary determination under the MMPA that the activity will have a negligible impact on the affected species.

EN07AP20.000

Detailed Description of Specific Activity

The procedures to be used for the proposed surveys would be similar to those used during previous seismic surveys by L-DEO and would use conventional seismic methodology. The surveys would involve one source vessel, R/V

Langseth,

which is owned by NSF and operated on its behalf by L-DEO. R/V

Langseth

would deploy an array of 36 airguns as an energy source with a total volume of ~6,600 in

3

. The array consists of 20 Bolt 1500LL airguns with volumes of 180 to 360 in

3

and 16 Bolt 1900LLX airguns with volumes of 40 to 120 in

3

. The airgun array configuration is illustrated in Figure 2-11 of NSF and USGS's Programmatic Environmental Impact Statement (PEIS; NSF-USGS, 2011). The vessel speed during seismic operations would be approximately 4.2 knots (~7.8 km/hour) during the survey and the airgun array would be towed at a depth of 12 m. The receiving system would consist of one 15-kilometer (km) long hydrophone streamer, OBSs, and OBNs. R/V

Oceanus,

which is owned by NSF and operated by Oregon State University, would be used to deploy the OBSs and OBNs. As the airguns are towed along the survey lines, the hydrophone streamer would transfer the data to the on-board processing system, and the OBSs and OBNs would receive and store the returning acoustic signals internally for later analysis.

Long 15-km-offset multichannel seismic (MCS) data would be acquired along numerous 2-D profiles oriented perpendicular to the margin and located

to provide coverage in areas inferred to be rupture patches during past earthquakes and their boundary zones. The survey would also include several strike lines including one continuous line along the continental shelf centered roughly over gravity-inferred fore-arc basins to investigate possible segmentation near the down-dip limit of the seismogenic zone. The margin normal lines would extend ~50 km seaward of the deformation front to image the region of subduction bend faulting in the incoming oceanic plate, and landward of the deformation front to as close to the shoreline as can be safely maneuvered. It is proposed that the southern transects off Oregon are acquired first, followed by the profiles off Washington and Vancouver Island, British Columbia.

The OBSs would consist of short-period multi-component OBSs from the Ocean Bottom Seismometer Instrument Center (OBSIC) and a large-

N

array of OBNs from a commercial provider to record shots along ~11 MCS margin-perpendicular profiles. OBSs would be deployed at 10-km spacing along ~11 profiles from Vancouver Island to Oregon, and OBNs would be deployed at a 500-m spacing along a portion of two profiles off Oregon. Two OBS deployments would occur with a total of 115 instrumented locations. 60 OBSs would be deployed to instrument seven profiles off Oregon, followed by a second deployment of 55 OBSs to instrument four profiles off Washington and Vancouver Island. The first deployment off Oregon would occur prior to the start of the proposed survey, after which R/V

Langseth

would acquire data in the southern portion of the study area. R/V

Oceanus

would start recovering the OBSs from deployment 1, and then re-deploy 55 OBSs off Washington and Vancouver Island, so that R/V

Langseth

can acquire data in the northern portion of the survey area. The OBSs have a height and diameter of ~1 m, and an ~80 kilogram (kg) anchor. To retrieve OBSs, an acoustic release transponder (pinger) is used to interrogate the instrument at a frequency of 8-11 kHz, and a response is received at a frequency of 11.5-13 kHz. The burn-wire release assembly is then activated, and the instrument is released to float to the surface from the anchor, which is not retrieved.

A total of 350 OBNs would be deployed: 229 nodes along one transect off northern Oregon, and 121 nodes along a second transect off central Oregon. The nodes are not connected to each other; each node is independent from each other, and there are no cables attached to them. Each node has internal batteries; all data is recorded and stored internally. The nodes weigh 21 kg in air (9.5 kg in water). As the OBNs are small (330 millimeters (mm) x 289 mm x 115 mm), compact, not buoyant, and lack an anchor-release mechanism, they cannot be deployed by free-fall as with the OBSs. The nodes would be deployed and retrieved using a remotely operated vehicle (ROV); the ROV would be deployed from R/V

Oceanus.

OBNs would be deployed 17 days prior to the start of the R/V

Langseth

cruise. The ROV would be fitted with a skid with capacity for 32 units, lowered to the seafloor, and towed at a speed of 0.6 knots at 5-10 m above the seafloor between deployment sites. After the 32 units are deployed, the ROV would be retrieved, the skid would be reloaded with another 32 units, and sent back to the seafloor for deployment, and so on. The ROV would recover the nodes 3 days after the completion of the R/V

Langseth

cruise. The nodes would be recovered one by one by a suction mechanism. Take of marine mammals is not expected to occur incidental to L-DEO's use of OBSs and OBNs.

In addition to the operations of the airgun array, a multibeam echosounder (MBES), a sub-bottom profiler (SBP), and an Acoustic Doppler Current Profiler (ADCP) would be operated from R/V

Langseth

continuously during the seismic surveys, but not during transit to and from the survey area. All planned geophysical data acquisition activities would be conducted by L-DEO with on-board assistance by the scientists who have proposed the studies. The vessel would be self-contained, and the crew would live aboard the vessel. Take of marine mammals is not expected to occur incidental to use of the MBES, SBP, or ADCP because they will be operated only during seismic acquisition, and it is assumed that, during simultaneous operations of the airgun array and the other sources, any marine mammals close enough to be affected by the MBES, SBP, and ADCP would already be affected by the airguns. However, whether or not the airguns are operating simultaneously with the other sources, given their characteristics (

e.g.,

narrow downward-directed beam), marine mammals would experience no more than one or two brief ping exposures, if any exposure were to occur. Proposed mitigation, monitoring, and reporting measures are described in detail later in this document (please see

Proposed Mitigation

and

Proposed Monitoring and Reporting

).

Description of Marine Mammals in the Area of Specified Activities

Sections 3 and 4 of the application summarize available information regarding status and trends, distribution and habitat preferences, and behavior and life history, of the potentially affected species. Additional information regarding population trends and threats may be found in NMFS's Stock Assessment Reports (SARs;

https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments

) and more general information about these species (

e.g.,

physical and behavioral descriptions) may be found on NMFS's website (

https://www.fisheries.noaa.gov/find-species

).

Table 1 lists all species with expected potential for occurrence in the survey area and summarizes information related to the population or stock, including regulatory status under the MMPA and ESA and potential biological removal (PBR), where known. For taxonomy, we follow Committee on Taxonomy (2019). PBR is defined by the MMPA as the maximum number of animals, not including natural mortalities, that may be removed from a marine mammal stock while allowing that stock to reach or maintain its optimum sustainable population (as described in NMFS's SARs). While no mortality is anticipated or authorized here, PBR and annual serious injury and mortality from anthropogenic sources are included here as gross indicators of the status of the species and other threats.

Marine mammal abundance estimates presented in this document represent the total number of individuals that make up a given stock or the total number estimated within a particular study or survey area. NMFS's stock abundance estimates for most species represent the total estimate of individuals within the geographic area, if known, that comprises that stock. For some species, this geographic area may extend beyond U.S. waters. All managed stocks in this region are assessed in NMFS's U.S. Pacific and Alaska SARs (Caretta

et al.,

2019; Muto

et al.,

2019). All MMPA stock information presented in Table 1 is the most recent available at the time of publication and is available in the 2018 SARs (Caretta

et al.,

2019; Muto

et al.,

2019) and draft 2019 SARs (available online at:

https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports

). Where available, abundance and status information is also presented

for marine mammals in Canadian waters in British Columbia.

Table 1—Marine Mammals That Could Occur in the Survey Area

Common name

Scientific name

Stock

ESA/MMPA

status;

strategic

(Y/N)

1

Stock abundance

(CV, N

min

, most recent abundance survey)

2

PBR

Annual

M/SI

3

Order Cetartiodactyla—Cetacea—Superfamily Mysticeti (baleen whales)

Family Eschrichtiidae:

Gray whale

Eschrichtius robustus

Eastern North Pacific

-/-; N

26,960 (0.05, 25,849, 2016)

801

138.

Family Balaenopteridae (rorquals):

Humpback whale

Megaptera novaeangliae

California/Oregon/Washington

-/-; Y

2,900 (0.05, 2,784, 2014)

16.7

>42.1.

Central North Pacific

-/-; Y

10,103 (0.30, 7,891, 2006)

83

25.

Minke whale

Balaenoptera acutorostrata

California/Oregon/Washington

-/-; N

636 (0.72, 369, 2014)

3.5

>1.3.

Sei whale

Balaenoptera borealis

Eastern North Pacific

E/D; Y

519 (0.4, 374, 2014)

0.75

>0.2.

Fin whale

Balaenoptera physalus

California/Oregon/Washington

E/D; Y

9,029 (0.12, 8,127, 2014)

81

>2.0.

Northeast Pacific

E/D; Y

3,168 (0.26, 2,554, 2013)

5.1

0.4.

Blue whale

Balaenoptera musculus

Eastern North Pacific

E/D; Y

1,496 (0.44, 1,050, 2014)

1.2

>19.4.

Superfamily Odontoceti (toothed whales, dolphins, and porpoises)

Family Physeteridae:

Sperm whale

Physeter macrocephalus

California/Oregon/Washington

E/D; Y

1,997 (0.57, 1,270, 2014)

2.5

0.4.

Family Kogiidae:

Pygmy sperm whale

Kogia breviceps

California/Oregon/Washington

-/-; N

4,111 (1.12, 1,924, 2014)

19

0.

Dwarf sperm whale

Kogia sima

California/Oregon/Washington

-/-; N

Unknown (Unknown, Unknown, 2014)

Undetermined

0.

Family Ziphiidae (beaked whales):

Cuvier's beaked whale

Ziphius cavirostris

California/Oregon/Washington

-/-; N

3,274 (0.67, 2,059, 2014)

21

<0.1.

Baird's beaked whale

Berardius bairdii

California/Oregon/Washington

-/-; N

2,697 (0.6, 1,633, 2014)

16

0

Blainville's beaked whale

Mesoplodon densirostris

California/Oregon/Washington

-/-; N

3,044 (0.54, 1,967, 2014)

20

0.1.

Hubbs' beaked whale

Mesoplodon carlshubbi

Stejneger's beaked whale

Mesoplodon stejnegeri

Family Delphinidae:

Bottlenose dolphin

Tursiops truncatus

California/Oregon/Washington offshore

-/-; N

1,924 (0.54, 1,255, 2014)

11

>1.6.

Striped dolphin

Stenella coeruleoalba

California/Oregon/Washington

-/-; N

29,211 (0.2, 24,782, 2014)

238

>0.8.

Common dolphin

Delphinus delphis

California/Oregon/Washington

-/-; N

969,861 (0.17, 839,325, 2014)

8,393

>40.

Pacific white-sided dolphin

Lagenorhynchus obliquidens

California/Oregon/Washington

-/-; N

26,814 (0.28, 21,195, 2014)

191

7.5.

British Columbia

4

N/A

22,160 (unknown, 16,522, 2008)

Unknown

Unknown.

Northern right whale dolphin

Lissodelphis borealis

California/Oregon/Washington

-/-; N

26,556 (0.44, 18,608, 2014)

179

3.8.

Risso's dolphin

Grampus griseus

California/Oregon/Washington

-/-; N

6,336 (0.32, 4,817, 2014)

46

>3.7.

False killer whale

Pseudorca crassidens

N/A

N/A

N/A

N/A

N/A.

Killer whale

Orcinus orca

Offshore

-/-; N

300 (0.1, 276, 2012)

2.8

0.

Southern Resident

E/D; Y

75 (N/A, 75, 2018)

0.13

0.

Northern Resident

-/-; N

302 (N/A, 302, 2018)

2.2

0.2.

West Coast Transient

-/-; N

243 (N/A, 243, 2009)

2.4

0.

Short-finned pilot whale

Globicephala macrorhynchus

California/Oregon/Washington

-/-; N

836 (0.79, 466, 2014)

4.5

1.2.

Family Phocoenidae (porpoises):

Harbor porpoise

Phocoena phocoena

Northern Oregon/Washington Coast

-/-; N

21,487 (0.44, 15,123, 2011)

151

>3.0.

Northern California/Southern Oregon

-/-; N

35,769 (0.52, 23,749, 2011)

475

>0.6.

British Columbia

4

N/A

8,091 (unknown, 4,885, 2008)

Unknown

Unknown.

Dall's porpoise

Phocoenoides dalli

California/Oregon/Washington

-/-; N

25,750 (0.45, 17,954, 2014)

172

0.3.

British Columbia

4

N/A

5,303 (unknown, 4,638, 2008)

Unknown

Unknown.

Order Carnivora—Superfamily Pinnipedia

Family Otariidae (eared seals and sea lions):

Northern fur seal

Callorhinus ursinus

Eastern Pacific

-/D; Y

620,660 (0.2, 525,333, 2016)

11,295

399.

California

-/D; N

14,050 (N/A, 7,524, 2013)

451

1.8.

California sea lion

Zalophus californianus

U.S.

-/-; N

257,606 (N/A, 233,515, 2014)

14,011

>321.

Steller sea lion

Eumetopias jubatus

Eastern U.S.

-/-; N

43,201 (see SAR, 43,201, 2017)

2,592

113.

British Columbia

4

N/A

4,037 (unknown, 1,100, 2008)

Unknown

Unknown.

Guadalupe fur seal

Arctocephalus philippii townsendi

Mexico to California

T/D; Y

34,187 (N/A, 31,019, 2013)

1,062

>3.8.

Family Phocidae (earless seals):

Harbor seal

Phoca vitulina

Oregon/Washington Coastal

-/-; N

Unknown (Unknown, Unknown, 1999)

Undetermined

10.6.

British Columbia

4

N/A

24,916 (Unknown, 19,666, 2008)

Unknown

Unknown.

Northern elephant seal

Mirounga angustirostris

California Breeding

-/-; N

179,000 (N/A, 81,368, 2010)

4,882

8.8.

1

Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.

2

NMFS marine mammal stock assessment reports online at:

https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments.

CV is coefficient of variation; N

min

is the minimum estimate of stock abundance. In some cases, CV is not applicable.

3

These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (

e.g.,

commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV associated with estimated mortality due to commercial fisheries is presented in some cases.

4

Best

et al.

(2015) total abundance estimates for animals in British Columbia based on surveys of the Strait of Georgia, Johnstone Strait, Queen Charlotte Sound, Hecate Strait, and Dixon Entrance.

All species that could potentially occur in the proposed survey areas are included in Table 1. However, additional species have been recorded in the specified geographic region but are considered sufficiently rare that take is not anticipated. The temporal and/or spatial occurrence of North Pacific right whales (

Eubalaena japonica

) is such that take is not expected to occur, and they are not discussed further beyond the explanation provided here. Only 82 sightings of right whales in the entire eastern North Pacific were reported from 1962 to 1999, with the majority of these occurring in the Bering Sea and adjacent areas of the Aleutian Islands (Brownell

et al.,

2001). Most sightings in the past 20 years have occurred in the southeastern Bering Sea, with a few in the Gulf of Alaska (Wade

et al.,

2011). Despite many miles of systematic aerial and ship-based surveys for marine mammals off the coasts of Washington, Oregon and California over several years, only seven documented sightings of right whales were made from 1990 to 2000 (Waite

et al.,

2003), and NMFS is not aware of any documented sightings in the area since then. Because of the small population size and the fact that North Pacific right whales spend the summer feeding in high latitudes, the likelihood that the proposed survey would encounter a North Pacific right whale is discountable.

In addition, the Northern sea otter (

Enhydra lutris kenyoni

) may be found in coastal waters of the survey area. However, sea otters are managed by the U.S. Fish and Wildlife Service and are not considered further in this document.

Gray Whale

Two separate populations for gray whales have been recognized in the North Pacific: The eastern North Pacific and the western North Pacific (or Korean-Okhotsk) stocks (LeDuc

et al.,

2002; Weller

et al.,

2013). However, the distinction between these two populations has been recently debated owing to evidence that whales from the western feeding area also travel to breeding areas in the eastern North Pacific (Weller

et al.,

2012, 2013; Mate

et al.,

2015). Thus it is possible that whales from either the ESA listed endangered Western North Pacific distinct population segment (DPS) or the delisted Eastern North Pacific DPS could occur in the survey area, although it is unlikely that a gray whale from the Western North Pacific DPS would be encountered during the time of the survey as they are expected to be in their feeding grounds in the western North Pacific at the time of the proposed survey. NMFS expects that any gray whales encountered by L-DEO during the proposed survey would be from the Eastern North Pacific DPS only, and is not proposing to authorize take of the endangered Western North Pacific DPS; therefore, the Western North Pacific DPS will not be discussed further in this document.

The eastern North Pacific gray whale breeds and winters in Baja California, and migrates north to summer feeding grounds in the northern Bering Sea, Chukchi Sea, and western Beaufort Sea (Rice and Wolman 1971; Rice 1998; Jefferson

et al.,

2015). The northward migration occurs from late February to June (Rice and Wolman 1971), with a peak in the Gulf of Alaska during mid-April (Braham 1984). Instead of migrating to arctic and sub-arctic waters, some individuals spend the summer months scattered along the coast from California to southeast Alaska (Rice and Wolman 1971; Nerini 1984; Darling

et al.,

1998; Calambokidis and Quan 1999; Dunham and Duffus 2001, 2002; Calambokidis

et al.,

2002, 2015, 2017). There is genetic evidence indicating the existence of this Pacific Coast Feeding Group (PCFG) is a

distinct local subpopulation (Frasier

et al.,

2011; Lang

et al.,

2014) and the United States and Canada recognize it as such (COSEWIC 2017; Caretta

et al.,

2019a). However, the status of the PCFG as a separate stock is currently unresolved (Weller

et al.,

2013). For the purposes of abundance estimates, the PCFG is defined as occurring between 41° N to 52° N from June 1 to November 30 (IWC 2012). The 2015 abundance estimate for the PCFG was 243 whales (Calambokidis

et al.,

2017); approximately 100 of those may occur in British Columbia during summer (Ford 2014). In British Columbia, most summer resident gray whales are found in Clayoquot Sound, Barkley Sound, and along the southwestern shore of Vancouver Island, and near Cape Caution on mainland British Columbia (Ford 2014). During surveys in British Columbia waters during summer, most sightings of gray whales were made within 10 km of shore and in water shallower than 100 m (Ford

et al.,

2010a). Two sightings of three gray whales were seen from R/V

Northern Light

during a survey off southern Washington in July 2012 (RPS 2012a).

Biologically Important Areas (BIAs) for feeding gray whales along the coasts of Washington, Oregon, and California have been identified, including northern Puget Sound, Northwestern Washington, and Grays Harbor in Washington, Depoe Bay and Cape Blanco and Orford Reef in Oregon, and Point St. George in California; most of these areas are of importance from late spring through early fall (Calambokidis

et al.,

2015). BIAs have also been identified for migrating gray whales along the entire coasts of Washington, Oregon, and California; although most whales travel within 10 km from shore, the BIAs were extended out to 47 km from the coastline (Calambokidis

et al.,

2015). The proposed surveys would occur during the late spring/summer feeding season, when most individuals from the eastern North Pacific stock occur farther north. Nonetheless, individual gray whales, particularly those from the PCFG could be encountered in nearshore waters of the proposed project area.

On May 30, 2019, NMFS declared an unusual mortality event (UME) for gray whales after elevated numbers of strandings occurred along the U.S. west coast. As of February 8, 2020, a total of 236 stranded gray whales have been reported, including 124 in the United States (48 in Alaska, 35 in Washington, 6 in Oregon, and 35 in California), 101 in Mexico, and 11 in Canada. Full or partial necropsy examinations were conducted on a subset of the whales. Preliminary findings in several of the whales have shown evidence of emaciation. These findings are not consistent across all of the whales examined, so more research is needed. The UME is ongoing, and NMFS continues to investigate the cause(s). Additional information about the UME is available at

https://www.fisheries.noaa.gov/national/marine-life-distress/2019-2020-gray-whale-unusual-mortality-event-along-west-coast.

Humpback Whale

The humpback whale is found throughout all of the oceans of the world (Clapham 2009). The worldwide population of humpbacks is divided into northern and southern ocean populations, but genetic analyses suggest some gene flow (either past or present) between the North and South Pacific (

e.g.,

Baker

et al.

1993; Caballero

et al.

2001). Geographical overlap of these populations has been documented only off Central America (Acevedo and Smultea 1995; Rasmussen

et al.

2004, 2007). Although considered to be mainly a coastal species, humpback whales often traverse deep pelagic areas while migrating (Clapham and Mattila 1990; Norris

et al.

1999; Calambokidis

et al.

2001).

Humpback whales migrate between summer feeding grounds in high latitudes and winter calving and breeding grounds in tropical waters (Clapham and Mead 1999). North Pacific humpback whales summer in feeding grounds along the Pacific Rim and in the Bering and Okhotsk seas (Pike and MacAskie 1969; Rice 1978; Winn and Reichley 1985; Calambokidis

et al.

2000, 2001, 2008). Humpback in the north Pacific winter in four different breeding areas: (1) Along the coast of Mexico; (2) along the coast of Central America; (3) around the main Hawaiian Islands; and (4) in the western Pacific, particularly around the Ogasawara and Ryukyu islands in southern Japan and the northern Philippines (Calambokidis

et al.

2008; Bettridge

et al.

2015).

Prior to 2016, humpback whales were listed under the ESA as an endangered species worldwide. Following a 2015 global status review (Bettridge

et al.,

2015), NMFS established 14 distinct population segments (DPS) with different listing statuses (81 FR 62259; September 8, 2016) pursuant to the ESA. The DPSs that occur in U.S. waters do not necessarily equate to the existing stocks designated under the MMPA and shown in Table 1. Because MMPA stocks cannot be portioned,

i.e.,

parts managed as ESA-listed while other parts managed as not ESA-listed, until such time as the MMPA stock delineations are reviewed in light of the DPS designations, NMFS considers the existing humpback whale stocks under the MMPA to be endangered and depleted for MMPA management purposes (

e.g.,

selection of a recovery factor, stock status).

Within the proposed survey area, three current DPSs may occur: The Hawaii DPS (not listed), Mexico DPS (threatened), and Central America DPS (endangered). According to Wade

et al.

(2017), the probability that whales encountered in Oregon and California waters are from a given DPS are as follows: Mexico DPS, 32.7 percent; Central America DPS, 67.2 percent; Hawaii DPS, 0 percent. The probability that humpback whales encountered in Washington and British Columbia waters are as follows: Mexico DPS, 27.9 percent; Central America DPS, 8.7 percent; Hawaii DPS, 63.5 percent.

Humpback whales are the most common species of large cetacean reported off the coasts of Oregon and Washington from May to November (Green

et al.,

1992; Calambokidis

et al.,

2000; 2004). The highest numbers have been reported off Oregon during May and June and off Washington during July-September. Humpbacks occur primarily over the continental shelf and slope during the summer, with few reported in offshore pelagic waters (Green

et al.,

1992; Calambokidis

et al.,

2004, 2015; Becker

et al.,

2012; Barlow 2016). Six humpback whale sightings (8 animals) were made off Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca plate seismic survey. There were 98 humpback whale sightings (213 animals) made during the July 2012 L-DEO seismic survey off southern Washington (RPS 2012a), and 11 sightings (23 animals) during the July 2012 L-DEO seismic survey off Oregon (RPS 2012c).

Humpback whales are common in the waters of British Columbia, where they occur in inshore, outer coastal, and continental shelf waters, as well as offshore (Ford 2014). Williams and Thomas (2007) estimated an abundance of 1,310 humpback whales in inshore coastal waters of British Columbia based on surveys conducted in 2004 and 2005. Best

et al.

(2015) provided an estimate of 1,029 humpbacks in British Columbia based on surveys during 2004-2008. In British Columbia, humpbacks are typically seen within 20 km from the coast, in water less than 500 m deep (Ford

et al.,

2010a). The greatest numbers of humpbacks are seen in British Columbia between April and November, although humpbacks are known to occur there throughout the

year (Ford

et al.,

2010a; Ford 2014). Humpback whales in British Columbia are thought to belong to at least two distinct feeding stocks; those identified off southern British Columbia show little interchange with those seen off northern British Columbia (Calambokidis

et al.,

2001, 2008). Humpback whales identified in southern British Columbia show a low level of interchange with those seen off California/Oregon/Washington (Calambokidis

et al.,

2001).

BIAs for feeding humpbacks along the coasts of Oregon and Washington, which have been described from May to November, are all within approximately 80 km from shore, and include the waters off northern Washington, and Stonewall and Heceta Bank, Oregon (Calambokidis

et al.,

2015). On October 9, 2019, NMFS issued a proposed rule to designate critical habitat in nearshore waters of the North Pacific Ocean for the endangered Central America DPS and the threatened Mexico DPS of humpback whale (NMFS 2019b). Critical habitat for the Central America DPS and Mexico DPS was proposed within the California Current Ecosystem (CCE) off the coasts California, Oregon, and Washington, representing areas of key foraging habitat. Off Washington and northern Oregon, the critical habitat would extend from the 50-m isobath out to the 1200-m isobath; off southern Oregon (south of 42°10′ N), it would extend out to the 2000-m isobath (NMFS 2019b).

Critical habitat for humpbacks has been designated in four locations in British Columbia (DFO 2013), including in the waters of the proposed survey area off southwestern Vancouver Island. The other three locations are located north of the proposed survey area at Haida Gwaii (Langara Island and Southeast Moresby Island) and at Gil Island (DFO 2013). These areas show persistent aggregations of humpback whales and have features such as prey availability, suitable acoustic environment, water quality, and physical space that allow for feeding, foraging, socializing, and resting (DFO 2013). Two of the proposed transect lines intersect the critical habitat on Swiftsure and La Pérouse Banks.

Minke Whale

The minke whale has a cosmopolitan distribution that spans from tropical to polar regions in both hemispheres (Jefferson

et al.

2015). In the Northern Hemisphere, the minke whale is usually seen in coastal areas, but can also be seen in pelagic waters during its northward migration in spring and summer and southward migration in autumn (Stewart and Leatherwood 1985). In the North Pacific, the summer range of the minke whale extends to the Chukchi Sea; in the winter, the whales move farther south to within 2° of the Equator (Perrin and Brownell 2009).

The International Whaling Commission (IWC) recognizes three stocks of minke whales in the North Pacific: The Sea of Japan/East China Sea, the rest of the western Pacific west of 180° N, and the remainder of the Pacific (Donovan 1991). Minke whales are relatively common in the Bering and Chukchi seas and in the Gulf of Alaska, but are not considered abundant in any other part of the eastern Pacific (Brueggeman

et al.

1990). In the far north, minke whales are thought to be migratory, but they are believed to be year-round residents in coastal waters off the west coast of the United States (Dorsey

et al.

1990).

Sightings of minke whales have been reported off Oregon and Washington in shelf and deeper waters (Green

et al.,

1992; Adams

et al.,

2014; Barlow 2016; Caretta

et al.,

2019a). There were no sightings of minke whales off Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca plate seismic survey or during the July 2012 L-DEO seismic survey off Oregon (RPS 2012b,c). One minke whale was seen during the July 2012 L-DEO seismic survey off southern Washington (RPS 2012a). Minke whales are sighted regularly in nearshore waters of British Columbia, but they are not considered abundant (COSEWIC 2006). They are most frequently sighted around the Gulf Islands and off northeastern Vancouver Island (Ford 2014). They are also regularly seen off the east coast of Moresby Island, and in Dixon Entrance, Hecate Strait, Queen Charlotte Sound, and the west coast of Vancouver Island were they occur in shallow and deeper water (Ford

et al.,

2010a; Ford 2014). Williams and Thomas (2007) estimated minke whale abundance for inshore coastal waters of British Columbia at 388 individuals based on surveys conducted in 2004 and 2005 while Best

et al.

(2015) provided an estimate of 522 minke whales based on surveys during 2004-2008.

Sei Whale

The distribution of the sei whale is not well known, but it is found in all oceans and appears to prefer mid-latitude temperate waters (Jefferson

et al.

2015). The sei whale is pelagic and generally not found in coastal waters (Jefferson

et al.

2015). It is found in deeper waters characteristic of the continental shelf edge region (Hain

et al.

1985) and in other regions of steep bathymetric relief such as seamounts and canyons (Kenney and Winn 1987; Gregr and Trites 2001). On feeding grounds, sei whales associate with oceanic frontal systems (Horwood 1987) such as the cold eastern currents in the North Pacific (Perry

et al.

1999a). Sei whales migrate from temperate zones occupied in winter to higher latitudes in the summer, where most feeding takes place (Gambell 1985a). During summer in the North Pacific, the sei whale can be found from the Bering Sea to the Gulf of Alaska and down to southern California, as well as in the western Pacific from Japan to Korea. Its winter distribution is concentrated at ~20° N (Rice 1998).

Sei whales are rare in the waters off California, Oregon, and Washington (Brueggeman

et al.,

1990; Green

et al.,

1992; Barlow 1994, 1997). Less than 20 confirmed sightings were reported in that region during extensive surveys between 1991 and 2014 (Green

et al.,

1992, 1993; Hill and Barlow 1992; Caretta and Forney 1993; Mangels and Gerrodette 1994; Von Saunder and Barlow 1999; Barlow 2003, 2010, 2014; Forney 2007; Carretta

et al.,

2019a). Two sightings of four individuals were made during the June-July 2012 L-DEO Juan de Fuca plate seismic survey off Washington/Oregon (RPS 2012b). No sei whales were sighted during the July 2012 L-DEO seismic surveys off Oregon and Washington (RPS 2012a,c).

The patterns of seasonal abundance found in whaling records suggested that the whales were caught as they migrated to summer feeding grounds, with the peak of the migration in July and offshore movement in summer, from ~25 km to ~100 km from shore (Gregr

et al.,

2000). Historical whaling data show that sei whales used to be distributed along the continental slope of British Columbia and over a large area off the northwest coast of Vancouver Island (Gregr and Trites 2001). Sei whales are now considered rare in Pacific waters of the United States and Canada; in British Columbia there were no sightings in the late 1900s after whaling ceased (Gregr

et al.,

2006). Ford (2014) only reported two sightings for British Columbia, both of those far offshore from Haida Gwaii. Possible sei whale vocalizations were detected off the west coast of Vancouver Island during spring and summer 2006 and 2007 (Ford

et al.,

2010b). Gregr and Trites (2001) proposed that the area off northwestern Vancouver Island and the continental slope may be critical habitat for sei whales because of favorable feeding conditions.

Fin Whale

The fin whale is widely distributed in all the world's oceans (Gambell 1985b), but typically occurs in temperate and polar regions from 20-70° north and south of the Equator (Perry

et al.

1999b). Northern and southern fin whale populations are distinct and are recognized as different subspecies (Aguilar 2009). Fin whales occur in coastal, shelf, and oceanic waters. Sergeant (1977) suggested that fin whales tend to follow steep slope contours, either because they detect them readily or because biological productivity is high along steep contours because of tidal mixing and perhaps current mixing. Stafford

et al.

(2009) noted that sea-surface temperature is a good predictor variable for fin whale call detections in the North Pacific.

Fin whales appear to have complex seasonal movements and are seasonal migrants; they mate and calve in temperate waters during the winter and migrate to feed at northern latitudes during the summer (Gambell 1985b). The North Pacific population summers from the Chukchi Sea to California and winters from California southwards (Gambell 1985b). Aggregations of fin whales are found year-round off southern and central California (Dohl

et al.

1980, 1983; Forney

et al.

1995; Barlow 1997) and in the summer off Oregon (Green

et al.

1992; Edwards

et al.

2015). Vocalizations from fin whales have also been detected year-round off northern California, Oregon, and Washington (Moore

et al.

1998, 2006; Watkins

et al.

2000a,b; Stafford

et al.

2007, 2009; Edwards

et al.

2015).

Eight fin whale sightings (19 animals) were made off Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca plate seismic survey; sightings were made in waters 2,369-3,940 m deep (RPS 2012b). Fourteen fin whale sightings (28 animals) were made during the July 2012 L-DEO seismic surveys off southern Washington (RPS 2012a). No fin whales were sighted during the July 2012 L-DEO seismic survey off Oregon (RPS 2012c). Fin whales were also seen off southern Oregon during July 2012 in water >2000 m deep during surveys by Adams

et al.

(2014).

Whaling records indicate fin whale occurrence off the west coast of British Columbia increased gradually from March to a peak in July, then decreased rapidly in September and October (Gregr

et al.,

2000). Fin whales occur throughout British Columbia waters near and past the continental shelf break, as well as in inshore waters (Ford 2014). Fin whales were the second most common cetacean sighted during DFO surveys in 2002-2008 (Ford

et al.,

2010a). They appear to be more common in northern British Columbia, but sightings have been made along the shelf edge and in deep waters off western Vancouver Island (Ford

et al.,

1994, 2010a; Calambokidis

et al.,

2003; Ford 2014). Acoustic detections have been made throughout the year in pelagic waters west of Vancouver Island (Edwards

et al.,

2015). Gregr and Trites (2001) proposed that the area off northwestern Vancouver Island and the continental slope may be critical habitat for fin whales because of favorable feeding conditions.

Blue Whale

The blue whale has a cosmopolitan distribution and tends to be pelagic, only coming nearshore to feed and possibly to breed (Jefferson

et al.

2015). Although it has been suggested that there are at least five subpopulations of blue whales in the North Pacific (NMFS 1998), analysis of blue whale calls monitored from the U.S. Navy Sound Surveillance System (SOSUS) and other offshore hydrophones (see Stafford

et al.,

1999, 2001, 2007; Watkins

et al.,

2000a; Stafford 2003) suggests that there are two separate populations: One in the eastern and one in the western North Pacific (Sears and Perrin 2009). Broad-scale acoustic monitoring indicates that blue whales occurring in the northeast Pacific during summer and fall may winter in the eastern tropical Pacific (Stafford

et al.,

1999, 2001).

The distribution of the species, at least during times of the year when feeding is a major activity, occurs in areas that provide large seasonal concentrations of euphausiids (Yochem and Leatherwood 1985). The eastern North Pacific stock feeds in California waters from June-November (Calambokidis

et al.,

1990; Mate

et al.,

1999). There are nine BIAs for feeding blue whales off the coast of California (Calambokidis

et al.,

2015), and core areas have also been identified there (Irvine

et al.,

2014).

Blue whales are considered rare off Oregon, Washington, and British Columbia (Buchanan

et al.,

2001; Gregr

et al.,

2006; Ford 2014), although satellite-tracked individuals have been reported off the coast (Bailey

et al.,

2009). Based on modeling of the dynamic topography of the region, blue whales could occur in relatively high densities off Oregon during summer and fall (Pardo

et al.,

2015: Hazen

et al.,

2017). Densities along the U.S. west coast, including Oregon, were predicted to be highest in shelf waters, with lower densities in deeper offshore areas (Becker

et al.,

2012; Calambokidis

et al.,

2015).

Sightings of blue whales in offshore waters of British Columbia are rare (Ford 2014; DFO 2017) and there is no abundance estimate for British Columbia waters (Nichol and Ford 2012). During surveys of British Columbia from 2002-2013, 16 sightings of blue whales were made, all of which occurred just to the south or west of Haida Gwaii during June, July, and August (Ford 2014). There have also been sightings off Vancouver Island during summer and fall (Calambokidis

et al.,

2004b; Ford 2014), with the most recent one reported off southwestern Haida Gwaii in July 2019 (CBC 2019).

Sperm Whale

The sperm whale is the largest of the toothed whales, with an extensive worldwide distribution (Rice 1989). Sperm whale distribution is linked to social structure: Mixed groups of adult females and juvenile animals of both sexes generally occur in tropical and subtropical waters, whereas adult males are commonly found alone or in same-sex aggregations, often occurring in higher latitudes outside the breeding season (Best 1979; Watkins and Moore 1982; Arnbom and Whitehead 1989; Whitehead and Waters 1990). Males can migrate north in the summer to feed in the Gulf of Alaska, Bering Sea, and waters around the Aleutian Islands (Kasuya and Miyashita 1988). Mature male sperm whales migrate to warmer waters to breed when they are in their late twenties (Best 1979).

Sperm whales generally are distributed over large areas that have high secondary productivity and steep underwater topography, in waters at least 1000 m deep (Jaquet and Whitehead 1996; Whitehead 2009). They are often found far from shore, but can be found closer to oceanic islands that rise steeply from deep ocean waters (Whitehead 2009). Adult males can occur in water depths <100 m and as shallow as 40 m (Whitehead

et al.,

1992; Scott and Sadove 1997). They can dive as deep as ~2 km and possibly deeper on rare occasions for periods of over 1 h; however, most of their foraging occurs at depths of ~300-800 m for 30-45 min (Whitehead 2003).

Sperm whales are distributed widely across the North Pacific (Rice 1989). Off California, they occur year-round (Dohl

et al.,

1983; Barlow 1995; Forney

et al.,

1995), with peak abundance from April to mid-June and from August to mid-November (Rice 1974). Off Oregon, sperm whales are seen in every season except winter (Green

et al.,

1992). Sperm whales were sighted during

surveys off Oregon in October 2011 and off Washington in June 2011 (Adams

et al.,

2014). Sperm whale sightings were also made off Oregon and Washington during the 2014 SWFSC vessel survey (Barlow 2016). A single sperm whale was sighted during a 2009 survey to the west of the proposed survey area (Holst 2017).

Oleson

et al.

(2009) noted a significant diel pattern in the occurrence of sperm whale clicks at offshore and inshore monitoring locations off Washington, whereby clicks were more commonly heard during the day at the offshore site and were more common at night at the inshore location, suggesting possible diel movements up and down the slope in search of prey. Sperm whale acoustic detections were also reported at the inshore site from June through January 2009, with an absence of calls during February to May (ŝirović

et al.,

2012). In addition, sperm whales were sighted during surveys off Washington in June 2011 and off Oregon in October 2011 (Adams

et al.

2014).

Whaling records report large numbers of sperm whales taken in April, with a peak in May. Analysis of data on catch locations, sex of the catch, and fetus lengths indicated that males and females were both 50-80 km from shore while mating in April and May, and that by July and August, adult females had moved to waters >100 km offshore to calve), and adult males had moved to within ~25 km of shore (Gregr

et al.,

2000). At least in the whaling era, females did not travel north of Vancouver Island whereas males were observed in deep water off Haida Gwaii (Gregr

et al.,

2000). After the whaling era, sperm whales have been sighted and detected acoustically in British Columbia waters throughout the year, with a peak during summer (Ford 2014). Acoustic detections at La Pérouse Bank off southwestern Vancouver Island have been recorded during spring and summer (Ford

et al.,

2010b). Sightings west of Vancouver Island and Haida Gwaii indicate that this species still occurs in British Columbia in small numbers (Ford

et al.,

1994; Ford 2014). Based on whaling data, Gregr and Trites (2001) proposed that the area off northwestern Vancouver Island and the continental slope may be critical habitat for male sperm whales because of favorable feeding conditions.

Pygmy and Dwarf Sperm Whales

The pygmy and dwarf sperm whales are distributed widely throughout tropical and temperate seas, but their precise distributions are unknown as most information on these species comes from strandings (McAlpine 2009). They are difficult to sight at sea, perhaps because of their avoidance reactions to ships and behavior changes in relation to survey aircraft (Würsig

et al.

1998). The two species are difficult to distinguish from one another when sighted (McAlpine 2009).

Both

Kogia

species are sighted primarily along the continental shelf edge and slope and over deeper waters off the shelf (Hansen

et al.

1994; Davis

et al.

1998). Several studies have suggested that pygmy sperm whales live mostly beyond the continental shelf edge, whereas dwarf sperm whales tend to occur closer to shore, often over the continental shelf (Rice 1998; Wang

et al.

2002; MacLeod

et al.

2004). Barros

et al.

(1998), on the other hand, suggested that dwarf sperm whales could be more pelagic and dive deeper than pygmy sperm whales. It has also been suggested that the pygmy sperm whale is more temperate and the dwarf sperm whale more tropical, based at least partially on live sightings at sea from a large database from the eastern tropical Pacific (Wade and Gerrodette 1993). This idea is also supported by the distribution of strandings in South American waters (Muñoz-Hincapié

et al.

1998).

Pygmy and dwarf sperm whales are rarely sighted off Oregon and Washington, with only one sighting of an unidentified

Kogia

spp. beyond the U.S. EEZ, during the 1991-2014 NOAA vessel surveys (Carretta

et al.,

2019a). Norman

et al.

(2004) reported eight confirmed stranding records of pygmy sperm whales for Oregon and Washington, five of which occurred during autumn and winter. There are several unconfirmed sighting reports of the pygmy sperm whale from the Canadian west coast (Baird

et al.,

1996). There is a stranding record of a pygmy sperm whale for northeastern Vancouver Island (Ford 2014), and there is a single dwarf sperm whale stranding record for southwestern Vancouver Island in September 1981 (Ford 2014). Willis and Baird (1998) state that the dwarf sperm whale is likely found in British Columbia waters more frequently than recognized, but Ford (2014) suggested that the presence of

Kogia

spp. in British Columbia waters is extralimital.

Cuvier's Beaked Whale

Cuvier's beaked whale is probably the most widespread of the beaked whales, although it is not found in polar waters (Heyning 1989). Cuvier's beaked whale appears to prefer steep continental slope waters (Jefferson

et al.

2015) and is most common in water depths >1000 m (Heyning 1989). It is mostly known from strandings and strands more commonly than any other beaked whale (Heyning 1989). Its inconspicuous blows, deep-diving behavior, and tendency to avoid vessels all help to explain the infrequent sightings (Barlow and Gisiner 2006). The population in the California Current Large Marine Ecosystem seems to be declining (Moore and Barlow 2013).

MacLeod

et al.

(2006) reported numerous sightings and strandings along the Pacific coast of the U.S. Cuvier's beaked whale is the most common beaked whale off the U.S. West Coast (Barlow 2010), and it is the beaked whale species that has stranded most frequently on the coasts of Oregon and Washington. From 1942-2010, there were 23 reported Cuvier's beaked whale strandings in Oregon and Washington (Moore and Barlow 2013). Most (75 percent) Cuvier's beaked whale strandings reported occurred in Oregon (Norman

et al.

2004). Records of Cuvier's beaked whale in British Columbia are scarce, although 20 strandings, one incidental catch, and five sightings have been reported, including off western Vancouver Island (Ford 2014). Most strandings have been reported in summer (Ford 2014).

Baird's Beaked Whale

Baird's beaked whale has a fairly extensive range across the North Pacific, with concentrations occurring in the Sea of Okhotsk and Bering Sea (Rice 1998; Kasuya 2009). In the eastern Pacific, Baird's beaked whale is reported to occur as far south as San Clemente Island, California (Rice 1998; Kasuya 2009). Two forms of Baird's beaked whales have been recognized, the common slate-gray form and a smaller, rare black form (Morin

et al.,

2017). The gray form is seen off Japan, in the Aleutians, and on the west coast of North America, whereas the black form has been reported for northern Japan and the Aleutians (Morin

et al.,

2017). Recent genetic studies suggest that the black form could be a separate species (Morin

et al.,

2017). Baird's beaked whales are currently divided into three distinct stocks: Sea of Japan, Okhotsk Sea, and Bering Sea/eastern North Pacific (Balcomb 1989; Reyes 1991). Baird's beaked whales are occasionally seen close to shore, but their primary habitat is in waters 1,000-3,000 m deep (Jefferson

et al.,

2015).

Along the U.S. west coast, Baird's beaked whales have been sighted primarily along the continental slope (Green

et al.,

1992; Becker

et al.,

2012; Caretta

et al.,

2019a) from late spring to early fall (Green

et al.,

1992). In the eastern North Pacific, Baird's beaked whales apparently spend the winter and

spring far offshore, and in June move onto the continental slop, where peak numbers occur during September and October. Green

et al.

(1992) noted that Baird's beaked whales on the U.S. west coast were most abundant in the summer, and were not sighted in the fall or winter.

Green

et al.

(1992) sighted five groups during 75,050 km of aerial survey effort in 1989-1990 off Washington/Oregon spanning coastal to offshore waters: two in slope waters and three in offshore waters. Two groups were sighted during summer/fall 2008 surveys off Washington/Oregon, in waters >2000 m deep (Barlow 2010). Acoustic monitoring offshore Washington detected Baird's beaked whale pulses during January through November 2011, with peaks in February and July (ŝirović

et al.

2012b

in

USN 2015). Baird's beaked whales were detected acoustically near the planned survey area in August 2016 during a SWFSC study using drifting acoustic recorders (Keating

et al.

2018).

There are whaler's reports of Baird's beaked whales off the west coast of Vancouver Island throughout the whaling season (May-September), especially in July and August (Reeves and Mitchell 1993). Twenty-four sightings have been made in British Columbia since the whaling era, including off the west coast of Vancouver Island (Ford 2014). Three strandings have also been reported, including one on northeastern Haida Gwaii and two on the west coast of Vancouver Island.

Blainville's Beaked Whale

Blainville's beaked whale is found in tropical and warm temperate waters of all oceans (Pitman 2009). It has the widest distribution throughout the world of all mesoplodont species and appears to be relatively common (Pitman 2009). Like other beaked whales, Blainville's beaked whale is generally found in waters 200-1400 m deep (Gannier 2000; Jefferson

et al.

2015). Blainville's beaked whale occurrences in cooler, higher-latitude waters are presumably related to warm-water incursions (Reeves

et al.

2002).

MacLeod

et al.

(2006) reported stranding and sighting records in the eastern Pacific ranging from 37.3° N to 41.5° S. However, none of the 36 beaked whale stranding records in Oregon and Washington during 1930-2002 included Blainville's beaked whale (Norman

et al.

2004). One Blainville's beaked whale was found stranded (dead) on the Washington coast in November 2016 (COASST 2016). There was one acoustic detection of Blainville's beaked whales recorded in Quinault Canyon off Washington in waters 1,400 m deep during 2011 (Baumann-Pickering

et al.,

2014).

Hubbs' Beaked Whale

Hubbs' beaked whale occurs in temperate waters of the North Pacific (Mead 1989). Its distribution appears to be correlated with the deep subarctic current (Mead

et al.

1982). Numerous stranding records have been reported for the U.S. West Coast (MacLeod

et al.

2006). Most of the records are from California, but it has been sighted as far north as Prince Rupert, British Columbia (Mead 1989). Two strandings are known from Washington/Oregon (Norman

et al.

2004). There have been no confirmed live sightings of Hubb's beaked whales in British Columbia.

Stejneger's Beaked Whale

Stejneger's beaked whale occurs in subarctic and cool temperate waters of the North Pacific Ocean (Mead 1989). In the eastern North Pacific Ocean, it is distributed from Alaska to southern California (Mead

et al.

1982; Mead 1989). Most stranding records are from Alaskan waters, and the Aleutian Islands appear to be its center of distribution (MacLeod

et al.

2006). After Cuvier's beaked whale, Stejneger's beaked whale was the second most commonly stranded beaked whale species in Oregon and Washington (Norman

et al.

2004). Stejneger's beaked whale calls were detected during acoustic monitoring off of Washington between January and June 2011, with an absence of calls from mid-July through November 2011 (ŝirović

et al.,

2012b in Navy 2015). Analysis of these data suggest that this species could be more than twice as prevalent in this area as Baird's beaked whale (Baumann-Pickering

et al.,

2014). At least five stranding records exist for British Columbia (Houston 1990b; Willis and Baird 1998; Ford 2014), including two strandings on the west coast of Haida Gwaii and two strandings on the west coast of Vancouver Island (Ford 2014). A possible sighting has been reported on the east coast of Vancouver Island (Ford 2014).

Bottlenose Dolphin

The bottlenose dolphin is distributed worldwide in coastal and shelf waters of tropical and temperate oceans (Jefferson

et al.

2015). There are two distinct bottlenose dolphin types: a shallow water type, mainly found in coastal waters, and a deep water type, mainly found in oceanic waters (Duffield

et al.

1983; Hoelzel

et al.

1998; Walker

et al.

1999). Coastal common bottlenose dolphins exhibit a range of movement patterns including seasonal migration, year-round residency, and a combination of long-range movements and repeated local residency (Wells and Scott 2009).

Bottlenose dolphins occur frequently off the coast of California, and sightings have been made as far north as 41° N, but few records exist for Oregon and Washington (Caretta

et al.,

2019a). Three sightings and one stranding of bottlenose dolphins have been documented in Puget Sound since 2004 (Cascadia Research 2011 in Navy 2015). During surveys off the U.S. West Coast, offshore bottlenose dolphins were generally found at distances greater than 1.86 miles (3 km) from the coast and were most abundant off southern California (Barlow, 2010, 2016). Based on sighting data collected by SWFSC during systematic surveys in the Northeast Pacific between 1986 and 2005, there were few sightings of offshore bottlenose dolphins north of about 40° N (Hamilton

et al.,

2009). Bottlenose dolphins occur frequently off the coast of California, and sightings have been made as far north as 41° N, but few records exist for Oregon/Washington (Carretta

et al.

2017). It is possible that bottlenose dolphins from the California/Oregon/Washington Offshore stock may range as far north as the proposed survey area during warm-water periods (Caretta

et al.,

2019a). Adams

et al.

(2014) recorded one sighting off Washington in September 2012. There are no confirmed records of bottlenose dolphins in British Columbia, though an unconfirmed record exists for offshore waters (Baird

et al.,

1993).

Striped Dolphin

The striped dolphin has a cosmopolitan distribution in tropical to warm temperate waters (Perrin

et al.

1994) and is generally seen south of 43° N (Archer 2009). However, in the eastern North Pacific, its distribution extends as far north as Washington (Jefferson

et al.,

2015). The striped dolphin is typically found in waters outside the continental shelf and is often associated with convergence zones and areas of upwelling (Archer 2009). However, it has also been observed approaching shore where there is deep water close to the coast (Jefferson

et al.

2015).

Striped dolphins regularly occur off California (Becker

et al.,

2012), including as far offshore as ~300 nmi (Caretta

et al.,

2019a). Striped dolphin encounters increase in deep, relatively warmer waters off the U.S. West Coast, and their abundance decreases north of

about 42°N (Barlow

et al.,

2009; Becker

et al.,

2012b; Becker

et al.,

2016; Forney

et al.,

2012). However, few sightings have been made off Oregon, and no sightings have been reported for Washington (Caretta

et al.,

2019a) but strandings have occurred along the coasts of both Washington and Oregon (Caretta

et al.,

2016). Striped dolphins are rare and considered extralimital in British Columbia (Ford 2014). There are a total of 14 confirmed records of stranded individuals or remains for Vancouver Island (Ford 2014). A single confirmed sighting was made in September 2019 in the Strait of Juan de Fuca (Pacific Whale Watch Association 2019).

Common Dolphin

The common dolphin is found in tropical and warm temperate oceans around the world (Perrin 2009). It ranges as far south as 40° S in the Pacific Ocean, is common in coastal waters 200-300 m deep and is also associated with prominent underwater topography, such as seamounts (Evans 1994). Common dolphins have been sighted as far as 550 km from shore (Barlow

et al.

1997).

The distribution of common dolphins along the U.S. West Coast is variable and likely related to oceanographic changes (Heyning and Perrin 1994; Forney and Barlow 1998). It is the most abundant cetacean off California; some sightings have been made off Oregon, in offshore waters (Carretta

et al.,

2017). During surveys off the west coast in 2014 and 2017, sightings were made as far north as 44° N (Barlow 2016; SIO n.d.). However, their abundance decreases dramatically north of about 40° N (Barlow

et al.,

2009; Becker

et al.,

2012c; Becker

et al.,

2016; Forney

et al.,

2012). Based on the absolute dynamic topography of the region, common dolphins could occur in relatively high densities off Oregon during July-December (Pardo

et al.,

2015). In contrast, habitat modeling predicted moderate densities of common dolphins off the Columbia River mouth during summer, with lower densities off southern Oregon (Becker

et al.

2014). There are three stranding records of common dolphins in British Columbia, including one from northwestern Vancouver Island, one from the Strait of Juan de Fuca, and one from Hecate Strait (Ford 2014).

Pacific White-Sided Dolphin

The Pacific white-sided dolphin is found in cool temperate waters of the North Pacific from the southern Gulf of California to Alaska. Across the North Pacific, it appears to have a relatively narrow distribution between 38° N and 47° N (Brownell

et al.,

1999). In the eastern North Pacific Ocean, including waters off Oregon, the Pacific white-sided dolphin is one of the most common cetacean species, occurring primarily in shelf and slope waters (Green

et al.,

1993; Barlow 2003, 2010). It is known to occur close to shore in certain regions, including (seasonally) southern California (Brownell

et al.,

1999).

Results of aerial and shipboard surveys strongly suggest seasonal north-south movements of the species between California and Oregon/Washington; the movements apparently are related to oceanographic influences, particularly water temperature (Green

et al.,

1993; Forney and Barlow 1998; Buchanan

et al.,

2001). During winter, this species is most abundant in California slope and offshore areas; as northern waters begin to warm in the spring, it appears to move north to slope and offshore waters off Oregon/Washington (Green

et al.,

1992, 1993; Forney 1994; Forney

et al.,

1995; Buchanan

et al.,

2001; Barlow 2003). The highest encounter rates off Oregon and Washington have been reported during March-May in slope and offshore waters (Green

et al.,

1992). Similarly, Becker

et al.

(2014) predicted relatively high densities off southern Oregon in shelf and slope waters.

Based on year-round aerial surveys off Oregon/Washington, the Pacific white-sided dolphin was the most abundant cetacean species, with nearly all (97 percent) sightings occurring in May (Green

et al.,

1992, 1993). Barlow (2003) also found that the Pacific white-sided dolphin was one of the most abundant marine mammal species off Oregon/Washington during 1996 and 2001 ship surveys, and it was the second most abundant species reported during 2008 surveys (Barlow 2010). Adams

et al.

(2014) reported numerous offshore sightings off Oregon during summer, fall, and winter surveys in 2011 and 2012.

Fifteen Pacific white-sided dolphin sightings (231 animals) were made off Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca plate seismic survey (RPS 2012b). There were fifteen Pacific white-sided dolphin sightings (462 animals) made during the July 2012 L-DEO seismic surveys off southern Washington (RPS 2012a). This species was not sighted during the July 2012 L-DEO seismic survey off Oregon (RPS 2012c). One group of 10 Pacific white-sided dolphins was sighted during the 2009 ETOMO survey (Holst 2017).

Pacific white-sided dolphins are common throughout the waters of British Columbia, including Dixon Entrance, Hecate Strait, Queen Charlotte Sound, the west coast of Haida Gwaii, as well as western Vancouver Island, and the mainland coast (Ford 2014). Stacey and Baird (1991a) compiled 156 published and unpublished records to 1988 of the Pacific white-sided dolphin within the Canadian 320-km extended EEZ. These dolphins move inshore and offshore seasonally (Stacey and Baird 1991a). There were inshore records for all months except July, and offshore records from all months except December. Offshore sightings were much more common than inshore sightings, especially in June-October; the mean water depth was ~1,100 m. Ford

et al.

(2011b) reported that most sightings occur in water depths <500 m and within 20 km from shore.

Northern Right Whale Dolphin

The northern right whale dolphin is found in cool temperate and sub-arctic waters of the North Pacific, from the Gulf of Alaska to near northern Baja California, ranging from 30° N to 50° N (Reeves

et al.,

2002). In the eastern North Pacific Ocean, including waters off Oregon, the northern right whale dolphin is one of the most common marine mammal species, occurring primarily in shelf and slope waters ~100 to >2000 m deep (Green

et al.,

1993; Barlow 2003). The northern right whale dolphin comes closer to shore where there is deep water, such as over submarine canyons (Reeves

et al.,

2002).

Aerial and shipboard surveys suggest seasonal inshore-offshore and north-south movements in the eastern North Pacific Ocean between California and Oregon/Washington; the movements are believed to be related to oceanographic influences, particularly water temperature and presumably prey distribution and availability (Green

et al.,

1993; Forney and Barlow 1998; Buchanan

et al.,

2001). Green

et al.

(1992, 1993) found that northern right whale dolphins were most abundant off Oregon/Washington during fall, less abundant during spring and summer, and absent during winter, when this species presumably moves south to warmer California waters (Green

et al.,

1992, 1993; Forney 1994; Forney

et al.,

1995; Buchanan

et al.,

2001; Barlow 2003).

Survey data suggest that, at least in the eastern North Pacific, seasonal inshore-offshore and north-south movements are related to prey availability, with peak abundance in the Southern California Bight during winter and distribution shifting northward into

Oregon and Washington as water temperatures increase during late spring and summer (Barlow, 1995; Becker

et al.,

2014; Forney

et al.,

1995; Forney & Barlow, 1998; Leatherwood & Walker, 1979). Seven northern right whale dolphin sightings (231 animals) were made off Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca plate seismic survey (RPS 2012b). There were eight northern right whale dolphin sightings (278 animals) made during the July 2012 L-DEO seismic surveys off southern Washington (RPS 2012a). This species was not sighted during the July 2012 L-DEO seismic survey off Oregon (RPS 2012c).

There are 47 records of northern right whale dolphins from British Columbia, mostly in deep water off the west coast of Vancouver Island; however, sightings have also been reported in deep water off Haida Gwaii (Ford 2014). Most sightings have occurred in water depths over 900 m (Baird and Stacey 1991a). One group of six northern right whale dolphins was seen west of Vancouver Island in water deeper than 2,500 m during a survey from Oregon to Alaska (Hauser and Holt 2009).

Risso's Dolphin

Risso's dolphin is distributed worldwide in temperate and tropical oceans (Baird 2009), although it shows a preference for mid-temperate waters of the shelf and slope between 30° and 45° N (Jefferson

et al.,

2014). Although it occurs from coastal to deep water (~200-1000 m depth), it shows a strong preference for mid-temperate waters of upper continental slopes and steep shelf-edge areas (Hartman 2018).

Off the U.S. West Coast, Risso's dolphin is believed to make seasonal north-south movements related to water temperature, spending colder winter months off California and moving north to waters off Oregon/Washington during the spring and summer as northern waters begin to warm (Green

et al.,

1992, 1993; Buchanan

et al.,

2001; Barlow 2003; Becker 2007). The distribution and abundance of Risso's dolphins are highly variable from California to Washington, presumably in response to changing oceanographic conditions on both annual and seasonal time scales (Forney and Barlow 1998; Buchanan

et al.

2001). The highest densities were predicted along the coasts of Washington, Oregon, and central and southern California (Becker

et al.,

2012). Off Oregon and Washington, Risso's dolphins are most abundant over continental slope and shelf waters during spring and summer, less so during fall, and rare during winter (Green

et al.,

1992, 1993). Green

et al.

(1992, 1993) reported most Risso's dolphin groups off Oregon between ~45 and 47º N. Several sightings were made off southern Oregon during surveys in 1991-2014 (Carretta

et al.,

2017). Sightings during ship surveys in summer/fall 2008 were mostly between ~30 and 38° N; none were reported in Oregon/Washington (Barlow 2010).Two sightings of 38 individuals were recorded off Washington from August 2004 to September 2008 (Oleson

et al.

2009). Risso's dolphins were sighted off Oregon, in June and October 2011 (Adams

et al.

2014). There were three Risso's dolphin sightings (31 animals) made during the July 2012 L-DEO seismic surveys off southern Washington (RPS 2012a). This species was not sighted during the July 2012 L-DEO seismic survey off Oregon (RPS 2012c), or off Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca plate seismic survey (RPS 2012b).

Risso's dolphin was once considered rare in British Columbia, but there have been numerous sightings since the 1970s (Ford 2014). Most sightings have been made in Gwaii Haanas National Park Reserve, Haida Gwaii, but there have also been sightings in Dixon Entrance, off the west coast of Haida Gwaii, Queen Charlotte Sound, and to the west of Vancouver Island (Ford 2014).

False Killer Whale

The false killer whale is found in all tropical and warmer temperate oceans, especially in deep, offshore waters (Odell and McClune 1999). It is widely distributed, but not abundant anywhere (Carwardine 1995). The false killer whale generally inhabits deep, offshore waters, but sometimes is found over the continental shelf and occasionally moves into very shallow (Jefferson

et al.,

2015; Baird 2018b). It is gregarious and forms strong social bonds, as is evident from its propensity to strand en masse (Baird 2018b). In the eastern North Pacific, it has been reported only rarely north of Baja California (Leatherwood

et al.,

1982, 1987; Mangels and Gerrodette 1994); however, the waters off the U.S. West Coast all the way north to Alaska are considered part of its secondary range (Jefferson

et al.

2015).

Its occurrence in Washington/Oregon is associated with warm-water incursions (Buchanan

et al.,

2001). One pod of false killer whales occurred in Puget Sound for several months during the 1990s (USN 2015). Two were reported stranded along the Washington coast between 1930-2002, both in El Niño years (Norman

et al.

2004). One sighting was made off southern California during 2014 (Barlow 2016).

Stacey and Baird (1991b) suggested that false killer whales are at the limit of their distribution in Canada and have always been rare. Sightings have been made along the northern and central mainland coast of British Columbia, as well as in Queen Charlotte Strait, Strait of Georgia, and along the west coast of Vancouver Island (Ford 2014).

Killer Whale

The killer whale is cosmopolitan and globally fairly abundant; it has been observed in all oceans of the world (Ford 2009). It is very common in temperate waters and also frequents tropical waters, at least seasonally (Heyning and Dahlheim 1988). There are three distinct ecotypes, or forms, of killer whales recognized in the north Pacific: Resident, transient, and offshore. The three ecotypes differ morphologically, ecologically, behaviorally, and genetically. Resident killer whales exclusively prey upon fish, with a clear preference for salmon (Ford and Ellis 2006; Hanson

et al.,

2010; Ford

et al.,

2016), while transient killer whales exclusively prey upon marine mammals (Caretta

et al.,

2019). Less is known about offshore killer whales, but they are believed to consume primarily fish, including several species of shark (Dahlheim

et al.,

2008).

Currently, there are eight killer whale stocks recognized in the U.S. Pacific: (1) Alaska Residents, occurring from southeast Alaska to the Aleutians and Bering Sea; (2) Northern Residents, from BC through parts of southeast Alaska; (3) Southern Residents, mainly in inland waters of Washington State and southern BC; (4) Gulf of Alaska, Aleutian Islands, and Bering Sea Transients, from Prince William Sound (PWS) through to the Aleutians and Bering Sea; (5) AT1 Transients, from PWS through the Kenai Fjords; (6) West Coast Transients, from California through southeast Alaska; (7) Offshore, from California through Alaska; and (8) Hawaiian (Carretta

et al.

2018). Individuals from the Southern Resident, Northern Resident, West Coast Transient, and Offshore stocks could be encountered in the proposed project area. All three pods (J, K, and L pods) of Southern Resident killer whales may occur in the project area.

Southern Resident killer whales mainly feed on salmon, in particular Chinook (

Oncorhynchus tshawytscha

), but also prey upon other salmonids, such as chum (

O. keta

), coho (

O. kitsutch

), and steelhead (

O. mykiss

), as well as rockfish (

Sebastes

spp.), Pacific

halibut (

Hippoglossus stenolepis

), Pacific herring (

Clupea pallasi

), among others. Seasonal and spatial shifts in prey consumption have been observed, with Chinook consumed in May through September, and chum eaten in the fall. Chinook remain an important prey item while the Southern Residents are in offshore coastal waters, where they also consume a greater diversity of fish species (NMFS 2019).

Southern Resident killer whales occur for part of the year in the inland waterways of the Salish Sea, including Puget Sound, the Strait of Juan de Fuca, and the southern Strait of Georgia mostly during the spring, summer, and fall. Their movement patterns appear related to the seasonal availability of prey, especially Chinook salmon. They also move to coastal waters, primarily off Washington and British Columbia, in search of suitable prey, and have been observed as far as central California and southeast Alaska (NMFS 2019). Although less is known about the whales' movements in outer coastal waters than inland waters of the Salish Sea, satellite tagging, opportunistic sighting, and acoustic recording data suggest that Southern Residents spend nearly all their time on the continental shelf, within 34 km of shore in water less than 200 m deep (Hanson

et al.,

2017).

The Southern Resident DPS was listed as endangered under the ESA in 2005 after a nearly 20 percent decline in abundance between 1996 and 2001 (70 FR 69903; November 18, 2005). As compared to stable or growing populations, the DPS reflects lower fecundity and has demonstrated little to no growth in recent decades, and in fact has declined further since the date of listing (NMFS 2019). The population abundance listed in the draft 2019 SARs is 75, from the July 1, 2018 annual census conducted by the Center for Whale Research (CWR) (Caretta

et al.,

2019); since that date, four whales have died or are presumed dead, and two calves were born in 2019, bringing the abundance to 73 whales (NMFS 2019). An additional adult male is considered missing as of January 2020 (CWR 2020). NMFS has identified three main causes of the population decline: (1) Reduced quantity and quality of prey; (2) persistent organic pollutants that could cause immune or reproductive system dysfunction; and (3) noise and disturbance from increased commercial and recreational vessel traffic (NMFS 2019).

The U.S. Southern Resident killer whale critical habitat designated under the ESA currently includes inland waters of Washington relative to a contiguous shoreline delimited by the line at a depth of 6.1 m relative to extreme high water (71 FR 69054; November 29, 2006). On September 19, 2019, NMFS published a proposed rule to revise designated Southern Resident killer whale critical habitat to include 40,472.7 km

2

of marine waters between the 6.1-m depth contour and the 200-m depth contour from the U.S. international border with Canada south to Point Sur, California (84 FR 49214; September 19, 2019). The proposed survey tracklines overlap with NMFS' proposed expanded Southern Resident critical habitat.

In Canada, Southern Resident killer whales are listed as Endangered under the Species at Risk Act (SARA), and critical habitat has been designated in the trans-boundary waters in southern British Columbia, including the southern Strait of Georgia, Haro Strait, and Strait of Juan de Fuca (SOR/2018-278, December 13, 2018; SOR/2009-68, February 19, 2009; DFO 2018). The continental shelf waters off southwestern Vancouver Island, including Swiftsure and La Pérouse Banks have also been designated as critical habitat (DFO 2018). Two of the proposed survey tracklines intersect the Canadian Southern Resident critical habitat on Swiftsure and La Pérouse Banks.

Northern Resident killer whales are not listed under the ESA, but are listed as threatened under Canada's SARA (DFO 2018). In British Columbia, Northern Resident killer whales inhabit the central and northern Strait of Georgia, Johnstone Strait, Queen Charlotte Strait, the west coast of Vancouver Island, and the entire central and north coast of mainland British Columbia (Muto

et al.,

2019a,b). Northern Resident killer whales are also regularly acoustically detected off the coast of Washington (Hanson

et al.,

2017). Canada has designated critical habitat for Northern Resident killer whales in Johnstone Strait, southeastern Queen Charlotte Strait, western Dixon Entrance along the north coast of Graham Island, Haida Gwaii, and Swiftsure and La Pérouse Banks off southwestern Vancouver Island (SOR/2018-278, December 13, 2018; SOR/2009-68, February 19, 2009; DFO 2018). Critical habitat for both Northern and Southern Resident killer whales has been established within the proposed survey area at Swiftsure and La Pérouse Banks (SOR/2018-278, December 13, 2018).

The main diet of transient killer whales consists of marine mammals, in particular porpoises and seals. West coast transient whales (also known as Bigg's killer whales) range from Southeast Alaska to California (Muto

et al.,

2019a). The seasonal movements of transients are largely unpredictable, although there is a tendency to investigate harbor seal haulouts off Vancouver Island more frequently during the pupping season in August and September (Baird 1994; Ford 2014). Transients have been sighted throughout British Columbia waters, including the waters around Vancouver Island (Ford 2014).

Little is known about offshore killer whales, but they occur primarily over shelf waters and feed on fish, especially sharks (Ford 2014). Dalheim

et al.

(2008) reported sightings in southeast Alaska during spring and summer. Relatively few sightings of offshore killer whales have been reported in British Columbia; there have been 103 records since 1988 (Ford 2014). The number of sightings are likely influenced by the fact that these whales prefer deeper waters near the continental slope, where little sighting effort has taken place (Ford 2014). Most sightings are from Haida Gwaii and 15 km or more off the west coast of Vancouver Island near the continental slope (Ford

et al.,

1994). Offshore killer whales are mainly seen off British Columbia during summer, but they can occur in British Columbia year-round (Ford 2014).

Short-Finned Pilot Whale

The short-finned pilot whale is found in tropical, subtropical, and warm temperate waters (Olson 2009); it is seen as far south as ~40° S and as far north as ~50° N (Jefferson

et al.

2015). Pilot whales are generally nomadic, but may be resident in certain locations, including California and Hawaii (Olson 2009). Short-finned pilot whales were common off southern California (Dohl

et al.

1980) until an El Niño event occurred in 1982-1983 (Carretta

et al.

2017).

Few sightings were made off California/Oregon/Washington in 1984-1992 (Green

et al.

1992; Carretta and Forney 1993; Barlow 1997), and sightings remain rare (Barlow 1997; Buchanan

et al.

2001; Barlow 2010). No short-finned pilot whales were seen during surveys off Oregon and Washington in 1989-1990, 1992, 1996, and 2001 (Barlow 2003). A few sightings were made off California during surveys in 1991-2014 (Barlow 2010). Carretta

et al.

(2019a) reported one sighting off Oregon during 1991-2014. Several stranding events in Oregon/southern Washington have been recorded over the past few decades, including in

March 1996, June 1998, and August 2002 (Norman

et al.

2004).

Short-finned pilot whales are considered rare in British Columbia waters (Baird and Stacey 1993; Ford 2014). There are 10 confirmed records, including three bycatch records in offshore waters, six sightings in offshore waters, and one stranding; the stranding occurred in the Strait of Juan de Fuca (Ford 2014). There are also unconfirmed records for nearshore waters of western Vancouver Island (Baird and Stacey 1993; Ford 2014).

Harbor Porpoise

The harbor porpoise inhabits temperate, subarctic, and arctic waters. It is typically found in shallow water (<100 m) nearshore but is occasionally sighted in deeper offshore water (Jefferson

et al.,

2015); abundance declines linearly as depth increases (Barlow 1988). In the eastern north Pacific, its range extends from Point Barrow, Alaska to Point Conception, California. Their seasonal movements appear to be inshore-offshore, rather than north-south, as a response to the abundance and distribution of food resources (Dohl

et al.,

1983; Barlow 1988). Genetic testing has also shown that harbor porpoises along the west coast of North America are not migratory and occupy restricted home ranges (Rosel

et al.,

1995).

Based on genetic data and density discontinuities, six stocks have been identified in California/Oregon/Washington: (1) Washington Inland Waters, (2) Northern Oregon/Washington Coast, (3) Northern California/Southern Oregon, (4) San Francisco-Russian River, (5) Monterey Bay, and (6) Morro Bay (Caretta

et al.,

2019a). Harbor porpoises form the Northern Oregon/Washington and the Northern California/Southern Oregon stocks could occur in the proposed project area (Caretta

et al.,

2019a).

Harbor porpoises inhabit coastal Oregon and Washington waters year-round, although there appear to be distinct seasonal changes in abundance there (Barlow 1988; Green

et al.,

1992). Green

et al.

(1992) reported that encounter rates were similarly high during fall and winter, intermediate during spring, and low during summer. Encounter rates were highest along the Oregon/Washington coast in the area from Cape Blanco (~43° N) to California, from fall through spring. During summer, the reported encounter rates decreased notably from inner shelf to offshore waters. Green

et al.

(1992) reported that 96 percent of harbor porpoise sightings off Oregon/Washington occurred in coastal waters <100 m deep, with a few sightings on the slope near the 200-m isobath. Similarly, predictive density distribution maps show the highest in nearshore waters along the coasts of Oregon/Washington, with very low densities beyond the 500-m isobath (Menza

et al.,

2016).

There were no harbor porpoise sightings made during the July 2012 L-DEO seismic surveys off southern Washington (RPS 2012a), the July 2012 L-DEO seismic survey off Oregon (RPS 2012c), or off Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca plate seismic survey (RPS 2012b).

Harbor porpoises are found along the coast of British Columbia year-round, primarily in coastal shallow waters, harbors, bays, and river mouths (Osborne

et al.,

1988), but can also be found in deep water over the continental shelf and over offshore banks that are no deeper than 150 m (Ford 2014; COSEWIC 2016). Many sightings records exist for nearshore waters of Vancouver Island, and occasional sightings have also been made in shallow water of Swiftsure and La Pérouse banks off southwestern Vancouver Island (Ford 2014).

Dall's Porpoise

Dall's porpoise is found in temperate to subarctic waters of the North Pacific and adjacent seas (Jefferson

et al.

2015). It is widely distributed across the North Pacific over the continental shelf and slope waters, and over deep ( ≥2500 m) oceanic waters (Hall 1979). It is probably the most abundant small cetacean in the North Pacific Ocean, and its abundance changes seasonally, likely in relation to water temperature (Becker 2007).

Off Oregon and Washington, Dall's porpoise is widely distributed over shelf and slope waters, with concentrations near shelf edges, but is also commonly sighted in pelagic offshore waters (Morejohn 1979; Green

et al.

1992; Becker

et al.

2014; Carretta

et al.

2018). Combined results of various surveys out to ~550 km offshore indicate that the distribution and abundance of Dall's porpoise varies between seasons and years. North-south movements are believed to occur between Oregon/Washington and California in response to changing oceanographic conditions, particularly temperature and distribution and abundance of prey (Green

et al.

1992, 1993; Mangels and Gerrodette 1994; Barlow 1995; Forney and Barlow 1998; Buchanan

et al.

2001). Becker

et al.

(2014) predicted high densities off southern Oregon throughout the year, with moderate densities to the north. According to predictive density distribution maps, the highest densities off southern Washington and Oregon occur along the 500-m isobath (Menza

et al.

2016).

Encounter rates reported by Green

et al.

(1992) during aerial surveys off Oregon/Washington were highest in fall, lowest during winter, and intermediate during spring and summer. Encounter rates during the summer were similarly high in slope and shelf waters, and somewhat lower in offshore waters (Green

et al.

1992). Dall's porpoise was the most abundant species sighted off Oregon/Washington during 1996, 2001, 2005, and 2008 ship surveys up to ~550 km from shore (Barlow 2003, 2010). Oleson

et al.

(2009) reported 44 sightings of 206 individuals off Washington during surveys from August 2004 to September 2008. Dall's porpoise were seen in the waters off Oregon during summer, fall, and winter surveys in 2011 and 2012 (Adams

et al.,

2014). Nineteen Dall's porpoise sightings (144 animals) were made off Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca plate seismic survey (RPS 2012b). There were 16 Dall's porpoise sightings (54 animals) made during the July 2012 L-DEO seismic surveys off southern Washington (RPS 2012a). This species was not sighted during the July 2012 L-DEO seismic survey off Oregon (RPS 2012c).

Dall's porpoise is found all along the coast of British Columbia and is common inshore and offshore throughout the year (Jefferson 1990; Ford 2014). It is most common over the continental shelf and slope, but also occurs >2,400 km from the coast (Pike and MacAskie 1969 in Jefferson 1990), and sightings have been made throughout the proposed survey area (Ford 2014). During a survey from Oregon to Alaska, Dall's porpoises were sighted west of Vancouver Island and Haida Gwaii in early October during the southbound transit, but none were sighted in mid-September during the northward transit; all sightings were made in water deeper than 2000 m (Hauser and Holst 2009).

Guadalupe Fur Seal

Guadalupe fur seals were once plentiful on the California coast, ranging from the Gulf of the Farallones near San Francisco, to the Revillagigedo Islands, Mexico (Aurioles-Gamboa

et al.,

1999), but they were over-harvested in the 19th century to near extinction. After being protected, the population grew slowly; mature individuals of the species were observed occasionally in the Southern California Bight starting in the 1960s (Stewart

et al.,

1993), and, in 1997, a

female and pup were observed on San Miguel Island (Melin & DeLong, 1999). Since 2008, individual adult females, subadult males, and between one and three pups have been observed annually on San Miguel Island (Caretta

et al.,

2017).

During the summer breeding season, most adults occur at rookeries in Mexico (Caretta

et al.,

2019a,b; Norris 2017 in Navy 2019a,b). Following the breeding season, adult males tend to move northward to forage. Females have been observed feeding south of Guadalupe Island, making an average round trip of 2,375 km (Ronald and Gots 2003). Several rehabilitated Guadalupe fur seals that were satellite tagged and released in central California traveled as far north as British Columbia (Norris

et al.,

2015; Norris 2017 in Navy 2019a,b). Fur seals younger than two years old are more likely to travel to more northerly, offshore areas than older fur seals (Norris 2017 in Navy 2019a,b). Stranding data also indicates that fur seals younger than two years old are more likely to occur in the proposed survey area, as this age class was most frequently reported (Lambourn

et al.,

2012 in Navy 2019a,b). Guadalupe fur seals have not been observed in previous L-DEO surveys in the northeast Pacific (RPS 2012a,b,c).

Increased strandings of Guadalupe fur seals have occurred along the entire coast of California. Guadalupe fur seal strandings began in January 2015 and were eight times higher than the historical average. Strandings have continued since 2015 and have remained well above average through 2019. Strandings are seasonal and generally peak in April through June of each year. Strandings in Oregon and Washington became elevated starting in 2019 and have continued to present. Strandings in these two states in 2019 are five times higher than the historical average. Guadalupe fur seals have stranded alive and dead. Those stranding are mostly weaned pups and juveniles (1-2 years old). The majority of stranded animals showed signs of malnutrition with secondary bacterial and parasitic infections. NMFS has declared a UME for Guadalupe fur seals along the entire U.S. West Coast; the UME is ongoing and NMFS is continuing to investigate the cause(s). For additional information on the UME, see

https://www.fisheries.noaa.gov/national/marine-life-distress/2015-2020-guadalupe-fur-seal-unusual-mortality-event-california.

Northern Fur Seal

The northern fur seal is endemic to the North Pacific Ocean and occurs from southern California to the Bering Sea, Sea of Okhotsk, and Sea of Japan (Jefferson

et al.

2015). The worldwide population of northern fur seals has declined substantially from 1.8 million animals in the 1950s (Muto

et al.

2018). They were subjected to large-scale harvests on the Pribilof Islands to supply a lucrative fur trade. Two stocks are recognized in U.S. waters: The Eastern North Pacific and the California stocks. The Eastern Pacific stock ranges from southern California during winter to the Pribilof Islands and Bogoslof Island in the Bering Sea during summer (Carretta

et al.

2018; Muto

et al.

2018). Abundance of the Eastern Pacific Stock has been decreasing at the Pribilof Islands since the 1940s and increasing on Bogoslof Island. The California stock originated with immigrants from the Pribilof Islands and Russian populations that recolonized San Miguel Island during the late 1950s or early 1960s after northern fur seals were extirpated from California in the 1700s and 1800s (DeLong 1982). The northern fur seal population appears to be greatly affected by El Niño events. In the month of June, approximately 93.6 percent of the northern fur seals in the survey area are expected to be from the Eastern Pacific stock and 6.4 percent from the California stock (U.S. Navy 2019). Therefore, although individuals from both the Eastern Pacific Stock and California Stock may be present in the proposed survey area, the majority are expected to be from the Eastern Pacific Stock.

Most northern fur seals are highly migratory. During the breeding season, most of the world's population of northern fur seals occurs on the Pribilof and Bogoslof islands (NMFS 2007). The main breeding season is in July (Gentry 2009). Adult males usually occur onshore from May to August, though some may be present until November; females are usually found ashore from June to November (Muto

et al.

2018). Nearly all fur seals from the Pribilof Island rookeries are foraging at sea from fall through late spring. In November, females and pups leave the Pribilof Islands and migrate through the Gulf of Alaska to feeding areas primarily off the coasts of BC, Washington, Oregon, and California before migrating north again to the rookeries in spring (Ream

et al.

2005; Pelland

et al.

2014). Immature seals can remain in southern foraging areas year-round until they are old enough to mate (NMFS 2007). Adult males migrate only as far south as the Gulf of Alaska or to the west off the Kuril Islands (Kajimura 1984). Pups from the California stock also migrate to Washington, Oregon, and northern California after weaning (Lea

et al.

2009). Although pups may be present, there are no rookeries in Washington or Oregon.

The northern fur seals spends ~90 percent of its time at sea, typically in areas of upwelling along the continental slopes and over seamounts (Gentry 1981). The remainder of its life is spent on or near rookery islands or haulouts. While at sea, northern fur seals usually occur singly or in pairs, although larger groups can form in waters rich with prey (Antonelis and Fiscus 1980; Gentry 1981). Northern fur seals dive to relatively shallow depths to feed: 100-200 m for females, and <400 m for males (Gentry 2009). Tagged adult female fur seals were shown to remain within 200 km of the shelf break (Pelland

et al.

2014).

Bonnell

et al.

(1992) noted the presence of northern fur seals year-round off Oregon/Washington, with the greatest numbers (87 percent) occurring in January-May. Northern fur seals were seen as far out from the coast as 185 km, and numbers increased with distance from land; they were 5-6 times more abundant in offshore waters than over the shelf or slope (Bonnell

et al.

1992). The highest densities were seen in the Columbia River plume (~46° N) and in deep offshore waters (>2000 m) off central and southern Oregon (Bonnell

et al.

1992). The waters off Washington are a known foraging area for adult females, and concentrations of fur seals were also reported to occur near Cape Blanco, Oregon, at ~42.8° N (Pelland

et al.

2014). Tagged adult fur seals were tracked from the Pribilof Islands to the waters off Washington/Oregon/California, with recorded movement throughout the proposed survey area (Pelland

et al.

2014).

Thirty-one northern fur seal sightings (63 animals) were made off Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca plate seismic survey (RPS 2012b). There were six sightings (6 animals) made during the July 2012 L-DEO seismic surveys off southern Washington (RPS 2012a). This species was not sighted during the July 2012 L-DEO seismic survey off Oregon (RPS 2012c).

Off British Columbia, females and subadult males are typically found during the winter off the continental shelf (Bigg 1990). They start arriving from Alaska during December and most will leave British Columbia waters by July (Ford 2014). Ford (2014) also reported the occurrence of northern fur seals throughout British Columbia, including Dixon Entrance, Hecate Strait, Queen Charlotte Sound, and off the west

coasts of Haida Gwaii and Vancouver Island, with concentrations over the shelf and slope, especially on La Pérouse Bank, southwestern Vancouver Island. A few animals are seen in inshore waters in British Columbia, and individuals occasionally come ashore, usually at sea lion haulouts (

e.g.,

Race Rocks, off southern Vancouver Island) during winter and spring (Baird and Hanson 1997). Although fur seals sometimes haul out in British Columbia, there are no breeding rookeries.

Steller Sea Lion

The Steller sea lion occurs along the North Pacific Rim from northern Japan to California (Loughlin

et al.,

1984). It is distributed around the coasts to the outer shelf from northern Japan through the Kuril Islands and Okhotsk Sea, through the Aleutian Islands, central Bering Sea, southern Alaska, and south to California (NOAA 2019d). There are two stocks and DPSs of Steller sea lions, the Western and Eastern DPSs, which are divided at 144° W longitude (Muto

et al.,

2019b). The Western DPS is listed as endangered under the ESA and includes animals that occur in Japan and Russia (Muto

et al.,

2019a,b); the Eastern DPS is not listed. Only individuals from the Eastern DPS are expected to occur in the proposed survey area.

Steller sea lions typically inhabit waters from the coast to the outer continental shelf and slope throughout their range; they are not considered migratory although foraging animals can travel long distances (Loughlin

et al.,

2003; Raum-Suryan

et al.,

2002). The eastern stock of Steller sea lions has historically bred on rookeries located in Southeast Alaska, British Columbia, Oregon, and California. However, within the last several years a new rookery has become established on the outer Washington coast (at the Carroll Island and Sea Lion Rock complex), with >100 pups born there in 2015 (Muto

et al.,

2018). Breeding adults occupy rookeries from late-May to early-July (NMFS 2008). Federally designated critical habitat for Steller sea lions in Oregon and California includes all rookeries (NMFS 1993). Although the Eastern DPS was delisted from the ESA in 2013, the designated critical habitat remains valid (NOAA 2019e). The critical habitat in Oregon is located along the coast at Rogue Reef (Pyramid Rock) and Orford Reef (Long Brown Rock and Seal Rock). The critical habitat area includes aquatic zones that extend 0.9 km seaward and air zones extending 0.9 km above these terrestrial and aquatic zones (NMFS 1993).

Non-breeding adults use haulouts or occupy sites at the periphery of rookeries during the breeding season (NMFS 2008). Pupping occurs from mid-May to mid-July (Pitcher and Calkins 1981) and peaks in June (Pitcher

et al.,

2002). Territorial males fast and remain on land during the breeding season (NMFS 2008). Females with pups generally stay within 30 km of the rookeries in shallow (30-120 m) water when feeding (NMFS 2008). Tagged juvenile sea lions showed localized movements near shore (Briggs

et al.,

2005). Loughlin

et al.

(2003) reported that most (88 percent) at-sea movements of juvenile Steller sea lions were short (< 15 km) foraging trips. Although Steller sea lions are not considered migratory, foraging animals can travel long distances outside of the breeding season (Loughlin

et al.,

2003; Raum-Suryan

et al.,

2002). During the summer, they mostly forage within 60 km from the coast; during winter they can range up to 200 km from shore (Ford 2014).

During a survey off Washington/Oregon June-July 2012, two Steller sea lions were seen from R/V Langseth (RPS 2012b) off southern Oregon. Eight sightings of 11 individuals were made from R/V Northern Light during a survey off southern Washington during July 2012 (RPS 2012a).

In British Columbia there are six main rookeries which are situated at the Scott Islands off northwestern Vancouver Island, the Kerourd Islands near Cape St. James at the southern end of Haida Gwaii, North Danger Rocks in eastern Hecate Strait, Virgin Rocks in eastern Queen Charlotte Sound, Garcin Rocks off southeastern Moresby Island in Haida Gwaii, and Gosling Rocks on the central mainland coast (Ford 2014). The Scott Islands and Cape St. James rookeries are the two largest breeding sites with 4,000 and 850 pups born in 2010, respectively (Ford 2014). Some adults and juveniles are also found on sites known as year-round haulouts during the breeding season. Haulouts are located along the coasts of Haida Gwaii, the central and northern mainland coast, the west coast of Vancouver Island, and the Strait of Georgia; some are year-round sites whereas others are only winter haulouts (Ford 2014). Pitcher

et al.

(2007) reported 24 major haulout sites (>50 sea lions) in British Columbia, but there are currently around 30 (Ford 2014). The total pup and non-pup count of Steller sea lions in British Columbia in 2002 was 15,438; this represents a minimum population estimate (Pitcher

et al.,

2007). The highest pup counts in British Columbia occur in July (Bigg 1988).

California Sea Lion

The primary range of the California sea lion includes the coastal areas and offshore islands of the eastern North Pacific Ocean from British Columbia to central Mexico, including the Gulf of California (Jefferson

et al.,

2015). However, its distribution is expanding (Jefferson

et al.,

2015), and its secondary range extends into the Gulf of Alaska (Maniscalco

et al.,

2004) and southern Mexico (Gallo-Reynoso and Solórzano-Velasco 1991), where it is occasionally recorded.

In California and Baja California, births occur on land from mid-May to late-June. During August and September, after the mating season, the adult males migrate northward to feeding areas as far north as Washington (Puget Sound) and British Columbia (Lowry

et al.,

1992). They remain there until spring (March-May), when they migrate back to the breeding colonies (Lowry

et al.,

Weise

et al.,

2006). The distribution of immature California sea lions is less well known but some make northward migrations that are shorter in length than the migrations of adult males (Huber 1991). However, most immature seals are presumed to remain near the rookeries for most of the year, as are females and pups (Lowry

et al.,

1992). Peak numbers of California sea lions off Oregon and Washington occur during the fall (Bonnell

et al.,

1992). California sea lions have not been observed in previous L-DEO surveys in the northeast Pacific (RPS 2012a,b,c).

California sea lions used to be rare in British Columbia, but their numbers have increased substantially since the 1970s and 1980s (Ford 2014). Wintering California sea lion numbers have increased off southern Vancouver Island since the 1970s, likely as a result of the increasing California breeding population (Olesiuk and Bigg 1984). Several thousand occur in the waters of British Columbia from fall to spring (Ford 2014). Adult and subadult male California sea lions are mainly seen in British Columbia during the winter (Olesiuk and Bigg 1984). They are mostly seen off the west coast of Vancouver Island and in the Strait of Georgia, but they are also known to haul out along the coasts of Haida Gwaii, including Dixon Entrance, and the mainland (Ford 2014).

Elevated strandings of California sea lion pups have occurred in Southern California since January 2013 and NMFS has declared a UME. The UME is confined to pup and yearling California sea lions, many of which are emaciated, dehydrated, and underweight for their age. A change in the availability of sea

lion prey, especially sardines, a high value food source for nursing mothers, is a likely contributor to the large number of strandings. Sardine spawning grounds shifted further offshore in 2012 and 2013, and while other prey were available (market squid and rockfish), these may not have provided adequate nutrition in the milk of sea lion mothers supporting pups, or for newly-weaned pups foraging on their own. Although the pups showed signs of some viruses and infections, findings indicate that this event was not caused by disease, but rather by the lack of high quality, close-by food sources for nursing mothers. Current evidence does not indicate that this UME was caused by a single infectious agent, though a variety of disease-causing bacteria and viruses were found in samples from sea lion pups. Investigating and identifying the cause of this UME is a true public-private effort with many collaborators. The investigative team examined multiple potential explanations for the high numbers of malnourished California sea lion pups observed on the island rookeries and stranded on the mainland in 2013. The UME investigation is ongoing. For more information, see

https://www.fisheries.noaa.gov/national/marine-life-distress/2013-2017-california-sea-lion-unusual-mortality-event-california.

Northern Elephant Seal

The northern elephant seal breeds in California and Baja California, primarily on offshore islands, from Cedros off the west coast of Baja California, north to the Farallons in Central California (Stewart

et al.

1994). Pupping has also been observed at Shell Island (~43.3° N) off southern Oregon, suggesting a range expansion (Bonnell

et al.

1992; Hodder

et al.

1998).

Adult elephant seals engage in two long northward migrations per year, one following the breeding season, and another following the annual molt (Stewart and DeLong 1995). Between the two foraging periods, they return to land to molt, with females returning earlier than males (March-April vs. July-August). After the molt, adults then return to their northern feeding areas until the next winter breeding season. Breeding occurs from December to March (Stewart and Huber 1993). Females arrive in late December or January and give birth within ~1 week of their arrival. Pups are weaned after just 27 days and are abandoned by their mothers. Juvenile elephant seals typically leave the rookeries in April or May and head north, traveling an average of 900-1000 km. Hindell (2009) noted that traveling likely takes place at depths >200 m. Most elephant seals return to their natal rookeries when they start breeding (Huber

et al.

1991).

When not at their breeding rookeries, adults feed at sea far from the rookeries. Males may feed as far north as the eastern Aleutian Islands and the Gulf of Alaska, whereas females feed south of 45° N (Le Boeuf

et al.

1993; Stewart and Huber 1993). Adult male elephant seals migrate north via the California current to the Gulf of Alaska during foraging trips, and could potentially be passing through the area off Washington in May and August (migrating to and from molting periods) and November and February (migrating to and from breeding periods), but likely their presence there is transient and short-lived. Adult females and juveniles forage in the California current off California to BC (Le Boeuf

et al.

1986, 1993, 2000). Bonnell

et al.

(1992) reported that northern elephant seals were distributed equally in shelf, slope, and offshore waters during surveys conducted off Oregon and Washington, as far as 150 km from shore, in waters >2000 m deep. Telemetry data indicate that they range much farther offshore than that (Stewart and DeLong 1995).

Off Washington, most elephant seal sightings at sea were made during June, July, and September; off Oregon, sightings were recorded from November through May (Bonnell

et al.

1992). Several seals were seen off Oregon during summer, fall, and winter surveys in 2011 and 2012 (Adams

et al.

2014). Northern elephant seals were also taken as bycatch off Oregon in the west coast groundfish fishery during 2002-2009 (Jannot

et al.

2011). Northern elephant seals were sighted five times (5 animals) during the July 2012 L-DEO seismic surveys off southern Washington (RPS 2012a). This species was not sighted during the July 2012 L-DEO seismic survey off Oregon (RPS 2012c), or off Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca plate seismic survey (RPS 2012b). One northern elephant seal was sighted during the 2009 ETOMO survey off of British Columbia (Holst 2017).

Race Rocks Ecological Preserve, located off southern Vancouver Island, is one of the few spots in British Columbia where elephant seals regularly haul out. Based on their size and general appearance, most animals using Race Rocks are adult females or subadults, although a few males also haul out there. Use of Race Rocks by northern elephant seals has increased substantially in recent years, most likely as a result of the species' dramatic recovery from near extinction in the early 20th century and its tendency to be highly migratory. A peak number (22) of adults and subadults were observed in spring 2003 (Demarchi and Bentley 2004); pups have also been born there primarily during December and January (Ford 2014). Haulouts can also be found on the western and northeastern coasts of Haida Gwaii, and along the coasts of Vancouver Island (Ford 2014).

Harbor Seal

Two subspecies of harbor seal occur in the Pacific:

P.v. stejnegeri

in the northwest Pacific Ocean and

P.v. richardii

in the eastern Pacific Ocean.

P.v. richardii

occurs in nearshore, coastal, and estuarine areas ranging from Baja California, Mexico, north to the Pribilof Islands in Alaska (Carretta

et al.,

2019a). Five stocks of harbor seals are recognized along the U.S. West Coast: (1) Southern Puget Sound, (2) Washington Northern Inland Waters Stock, (3) Hood Canal, (4) Oregon/Washington Coast, and (5) California (Carretta

et al.,

2019a). The Oregon/Washington Coast stock occurs in the proposed survey area.

Harbor seals inhabit estuarine and coastal waters, hauling out on rocks, reefs, beaches, and glacial ice flows. They are generally non-migratory, but move locally with the tides, weather, season, food availability, and reproduction (Scheffer and Slipp 1944; Fisher 1952; Bigg 1969, 1981). Female harbor seals give birth to a single pup while hauled out on shore or on glacial ice flows; pups are born from May to mid-July. When molting, which occurs primarily in late August, seals spend the majority of the time hauled out on shore, glacial ice, or other substrates. Juvenile harbor seals can travel significant distances (525 km) to forage or disperse (Lowry

et al.,

2001). The smaller home range used by adults is suggestive of a strong site fidelity (Pitcher and Calkins 1979; Pitcher and McAllister 1981; Lowry

et al.,

2001).

Harbor seals haul out on rocks, reefs, and beaches along the U.S. west coast (Carretta

et al.,

2019a). Jeffries

et al.

(2000) documented several harbor seal rookeries and haulouts along the Washington coastline. Bonnell

et al.

(1992) noted that most harbor seals sighted off Oregon and Washington were within 20 km from shore, with the farthest sighting 92 km from the coast. Menza

et al.

(2016) also showed the highest predicted densities nearshore. During surveys off the Oregon and Washington coasts, 88 percent of at-sea harbor seals occurred over shelf waters <200 m deep, with a few sightings near the 2000-m contour, and only one sighting over deeper water (Bonnell

et

al.,

1992). Twelve sightings of harbor seals occurred in nearshore waters from R/V

Northern Light

during a survey off southern Washington during July 2012 (RPS 2012a).

Harbor seals occur along all coastal areas of British Columbia, including the western coast of Vancouver Island, with the highest concentration in the Strait of Georgia (13.1 seals per km of coast); average densities elsewhere are 2.6 seals per km (Ford 2014). Almost 1,400 haulouts have been reported for British Columbia, many of them in the Strait of Georgia (Ford 2014).

Marine Mammal Hearing

Hearing is the most important sensory modality for marine mammals underwater, and exposure to anthropogenic sound can have deleterious effects. To appropriately assess the potential effects of exposure to sound, it is necessary to understand the frequency ranges marine mammals are able to hear. Current data indicate that not all marine mammal species have equal hearing capabilities (

e.g.,

Richardson

et al.,

1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall

et al.

(2007) recommended that marine mammals be divided into functional hearing groups based on directly measured or estimated hearing ranges on the basis of available behavioral response data, audiograms derived using auditory evoked potential techniques, anatomical modeling, and other data. Note that no direct measurements of hearing ability have been successfully completed for mysticetes (

i.e.,

low-frequency cetaceans). Subsequently, NMFS (2018) described generalized hearing ranges for these marine mammal hearing groups. Generalized hearing ranges were chosen based on the approximately 65 decibel (dB) threshold from the normalized composite audiograms, with the exception for lower limits for low-frequency cetaceans where the lower bound was deemed to be biologically implausible and the lower bound from Southall

et al.

(2007) retained. Marine mammal hearing groups and their associated hearing ranges are provided in Table 2.

Table 2—Marine Mammal Hearing Groups (NMFS, 2018)

Hearing group

Generalized hearing range *

Low-frequency (LF) cetaceans (baleen whales)

7 Hz to 35 kHz.

Mid-frequency (MF) cetaceans (dolphins, toothed whales, beaked whales, bottlenose whales)

150 Hz to 160 kHz.

High-frequency (HF) cetaceans (true porpoises,

Kogia,

river dolphins, cephalorhynchid,

Lagenorhynchus cruciger

&

L. australis

)

275 Hz to 160 kHz.

Phocid pinnipeds (PW) (underwater) (true seals)

50 Hz to 86 kHz.

Otariid pinnipeds (OW) (underwater) (sea lions and fur seals)

60 Hz to 39 kHz.

* Represents the generalized hearing range for the entire group as a composite (

i.e.,

all species within the group), where individual species' hearing ranges are typically not as broad. Generalized hearing range chosen based on ~65 dB threshold from normalized composite audiogram, with the exception for lower limits for LF cetaceans (Southall

et al.

2007) and PW pinniped (approximation).

The pinniped functional hearing group was modified from Southall

et al.

(2007) on the basis of data indicating that phocid species have consistently demonstrated an extended frequency range of hearing compared to otariids, especially in the higher frequency range (Hemilä

et al.,

2006; Kastelein

et al.,

2009; Reichmuth and Holt, 2013).

For more detail concerning these groups and associated frequency ranges, please see NMFS (2018) for a review of available information. 31 marine mammal species (25 cetacean and six pinniped (four otariid and two phocid) species) have the reasonable potential to co-occur with the proposed survey activities. Please refer to Table 1. Of the cetacean species that may be present, six are classified as low-frequency cetaceans (

i.e.,

all mysticete species), 15 are classified as mid-frequency cetaceans (

i.e.,

all delphinid and ziphiid species and the sperm whale), and four are classified as high-frequency cetaceans (

i.e.,

porpoises and

Kogia

spp.).

Potential Effects of Specified Activities on Marine Mammals and Their Habitat

This section includes a summary and discussion of the ways that components of the specified activity may impact marine mammals and their habitat. The

Estimated Take by Incidental Harassment

section later in this document includes a quantitative analysis of the number of individuals that are expected to be taken by this activity. The

Negligible Impact Analysis and Determination

section considers the content of this section, the

Estimated Take by Incidental Harassment

section, and the

Proposed Mitigation

section, to draw conclusions regarding the likely impacts of these activities on the reproductive success or survivorship of individuals and how those impacts on individuals are likely to impact marine mammal species or stocks.

Description of Active Acoustic Sound Sources

This section contains a brief technical background on sound, the characteristics of certain sound types, and on metrics used in this proposal inasmuch as the information is relevant to the specified activity and to a discussion of the potential effects of the specified activity on marine mammals found later in this document.

Sound travels in waves, the basic components of which are frequency, wavelength, velocity, and amplitude. Frequency is the number of pressure waves that pass by a reference point per unit of time and is measured in hertz (Hz) or cycles per second. Wavelength is the distance between two peaks or corresponding points of a sound wave (length of one cycle). Higher frequency sounds have shorter wavelengths than lower frequency sounds, and typically attenuate (decrease) more rapidly, except in certain cases in shallower water. Amplitude is the height of the sound pressure wave or the “loudness” of a sound and is typically described using the relative unit of the dB. A sound pressure level (SPL) in dB is described as the ratio between a measured pressure and a reference pressure (for underwater sound, this is 1 microPascal (μPa)) and is a logarithmic unit that accounts for large variations in amplitude; therefore, a relatively small change in dB corresponds to large changes in sound pressure. The source level (SL) represents the SPL referenced at a distance of 1 m from the source (referenced to 1 μPa) while the received level is the SPL at the listener's position (referenced to 1 μPa).

Root mean square (rms) is the quadratic mean sound pressure over the duration of an impulse. Root mean square is calculated by squaring all of the sound amplitudes, averaging the squares, and then taking the square root of the average (Urick, 1983). Root mean square accounts for both positive and negative values; squaring the pressures

makes all values positive so that they may be accounted for in the summation of pressure levels (Hastings and Popper, 2005). This measurement is often used in the context of discussing behavioral effects, in part because behavioral effects, which often result from auditory cues, may be better expressed through averaged units than by peak pressures.

Sound exposure level (SEL; represented as dB re 1 μPa

2

−s) represents the total energy contained within a pulse and considers both intensity and duration of exposure. Peak sound pressure (also referred to as zero-to-peak sound pressure or 0-p) is the maximum instantaneous sound pressure measurable in the water at a specified distance from the source and is represented in the same units as the rms sound pressure. Another common metric is peak-to-peak sound pressure (pk-pk), which is the algebraic difference between the peak positive and peak negative sound pressures. Peak-to-peak pressure is typically approximately 6 dB higher than peak pressure (Southall

et al.,

2007).

When underwater objects vibrate or activity occurs, sound-pressure waves are created. These waves alternately compress and decompress the water as the sound wave travels. Underwater sound waves radiate in a manner similar to ripples on the surface of a pond and may be either directed in a beam or beams or may radiate in all directions (omnidirectional sources), as is the case for pulses produced by the airgun arrays considered here. The compressions and decompressions associated with sound waves are detected as changes in pressure by aquatic life and man-made sound receptors such as hydrophones.

Even in the absence of sound from the specified activity, the underwater environment is typically loud due to ambient sound. Ambient sound is defined as environmental background sound levels lacking a single source or point (Richardson

et al.,

1995), and the sound level of a region is defined by the total acoustical energy being generated by known and unknown sources. These sources may include physical (

e.g.,

wind and waves, earthquakes, ice, atmospheric sound), biological (

e.g.,

sounds produced by marine mammals, fish, and invertebrates), and anthropogenic (

e.g.,

vessels, dredging, construction) sound. A number of sources contribute to ambient sound, including the following (Richardson

et al.,

1995):

•

Wind and waves:

The complex interactions between wind and water surface, including processes such as breaking waves and wave-induced bubble oscillations and cavitation, are a main source of naturally occurring ambient sound for frequencies between 200 Hz and 50 kHz (Mitson, 1995). In general, ambient sound levels tend to increase with increasing wind speed and wave height. Surf sound becomes important near shore, with measurements collected at a distance of 8.5 km from shore showing an increase of 10 dB in the 100 to 700 Hz band during heavy surf conditions;

•

Precipitation:

Sound from rain and hail impacting the water surface can become an important component of total sound at frequencies above 500 Hz, and possibly down to 100 Hz during quiet times;

•

Biological:

Marine mammals can contribute significantly to ambient sound levels, as can some fish and snapping shrimp. The frequency band for biological contributions is from approximately 12 Hz to over 100 kHz; and

•

Anthropogenic:

Sources of ambient sound related to human activity include transportation (surface vessels), dredging and construction, oil and gas drilling and production, seismic surveys, sonar, explosions, and ocean acoustic studies. Vessel noise typically dominates the total ambient sound for frequencies between 20 and 300 Hz. In general, the frequencies of anthropogenic sounds are below 1 kHz and, if higher frequency sound levels are created, they attenuate rapidly. Sound from identifiable anthropogenic sources other than the activity of interest (

e.g.,

a passing vessel) is sometimes termed background sound, as opposed to ambient sound.

The sum of the various natural and anthropogenic sound sources at any given location and time—which comprise “ambient” or “background” sound—depends not only on the source levels (as determined by current weather conditions and levels of biological and human activity) but also on the ability of sound to propagate through the environment. In turn, sound propagation is dependent on the spatially and temporally varying properties of the water column and sea floor, and is frequency-dependent. As a result of the dependence on a large number of varying factors, ambient sound levels can be expected to vary widely over both coarse and fine spatial and temporal scales. Sound levels at a given frequency and location can vary by 10-20 dB from day to day (Richardson

et al.,

1995). The result is that, depending on the source type and its intensity, sound from a given activity may be a negligible addition to the local environment or could form a distinctive signal that may affect marine mammals. Details of source types are described in the following text.

Sounds are often considered to fall into one of two general types: Pulsed and non-pulsed (defined in the following). The distinction between these two sound types is important because they have differing potential to cause physical effects, particularly with regard to hearing (

e.g.,

Ward, 1997 in Southall

et al.,

2007). Please see Southall

et al.

(2007) for an in-depth discussion of these concepts.

Pulsed sound sources (

e.g.,

airguns, explosions, gunshots, sonic booms, impact pile driving) produce signals that are brief (typically considered to be less than one second), broadband, atonal transients (ANSI, 1986, 2005; Harris, 1998; NIOSH, 1998; ISO, 2003) and occur either as isolated events or repeated in some succession. Pulsed sounds are all characterized by a relatively rapid rise from ambient pressure to a maximal pressure value followed by a rapid decay period that may include a period of diminishing, oscillating maximal and minimal pressures, and generally have an increased capacity to induce physical injury as compared with sounds that lack these features.

Non-pulsed sounds can be tonal, narrowband, or broadband, brief or prolonged, and may be either continuous or non-continuous (ANSI, 1995; NIOSH, 1998). Some of these non-pulsed sounds can be transient signals of short duration but without the essential properties of pulses (

e.g.,

rapid rise time). Examples of non-pulsed sounds include those produced by vessels, aircraft, machinery operations such as drilling or dredging, vibratory pile driving, and active sonar systems (such as those used by the U.S. Navy). The duration of such sounds, as received at a distance, can be greatly extended in a highly reverberant environment.

Airgun arrays produce pulsed signals with energy in a frequency range from about 10-2,000 Hz, with most energy radiated at frequencies below 200 Hz. The amplitude of the acoustic wave emitted from the source is equal in all directions (

i.e.,

omnidirectional), but airgun arrays do possess some directionality due to different phase delays between guns in different directions. Airgun arrays are typically tuned to maximize functionality for data acquisition purposes, meaning that sound transmitted in horizontal directions and at higher frequencies is minimized to the extent possible.

Acoustic Effects

Here, we discuss the effects of active acoustic sources on marine mammals.

Potential Effects of Underwater Sound

—Please refer to the information given previously (“Description of Active Acoustic Sources”) regarding sound, characteristics of sound types, and metrics used in this document. Note that, in the following discussion, we refer in many cases to a review article concerning studies of noise-induced hearing loss conducted from 1996-2015 (

i.e.,

Finneran, 2015). For study-specific citations, please see that work. Anthropogenic sounds cover a broad range of frequencies and sound levels and can have a range of highly variable impacts on marine life, from none or minor to potentially severe responses, depending on received levels, duration of exposure, behavioral context, and various other factors. The potential effects of underwater sound from active acoustic sources can potentially result in one or more of the following: Temporary or permanent hearing impairment, non-auditory physical or physiological effects, behavioral disturbance, stress, and masking (Richardson

et al.,

1995; Gordon

et al.,

2004; Nowacek

et al.,

2007; Southall

et al.,

2007; Götz

et al.,

2009). The degree of effect is intrinsically related to the signal characteristics, received level, distance from the source, and duration of the sound exposure. In general, sudden, high level sounds can cause hearing loss, as can longer exposures to lower level sounds. Temporary or permanent loss of hearing will occur almost exclusively for noise within an animal's hearing range. We first describe specific manifestations of acoustic effects before providing discussion specific to the use of airgun arrays.

Richardson

et al.

(1995) described zones of increasing intensity of effect that might be expected to occur, in relation to distance from a source and assuming that the signal is within an animal's hearing range. First is the area within which the acoustic signal would be audible (potentially perceived) to the animal, but not strong enough to elicit any overt behavioral or physiological response. The next zone corresponds with the area where the signal is audible to the animal and of sufficient intensity to elicit behavioral or physiological responsiveness. Third is a zone within which, for signals of high intensity, the received level is sufficient to potentially cause discomfort or tissue damage to auditory or other systems. Overlaying these zones to a certain extent is the area within which masking (

i.e.,

when a sound interferes with or masks the ability of an animal to detect a signal of interest that is above the absolute hearing threshold) may occur; the masking zone may be highly variable in size.

We describe the more severe effects of certain non-auditory physical or physiological effects only briefly as we do not expect that use of airgun arrays are reasonably likely to result in such effects (see below for further discussion). Potential effects from impulsive sound sources can range in severity from effects such as behavioral disturbance or tactile perception to physical discomfort, slight injury of the internal organs and the auditory system, or mortality (Yelverton

et al.,

1973). Non-auditory physiological effects or injuries that theoretically might occur in marine mammals exposed to high level underwater sound or as a secondary effect of extreme behavioral reactions (

e.g.,

change in dive profile as a result of an avoidance reaction) caused by exposure to sound include neurological effects, bubble formation, resonance effects, and other types of organ or tissue damage (Cox

et al.,

2006; Southall

et al.,

2007; Zimmer and Tyack, 2007; Tal

et al.,

2015). The survey activities considered here do not involve the use of devices such as explosives or mid-frequency tactical sonar that are associated with these types of effects.

Threshold Shift

—Marine mammals exposed to high-intensity sound, or to lower-intensity sound for prolonged periods, can experience hearing threshold shift (TS), which is the loss of hearing sensitivity at certain frequency ranges (Finneran, 2015). TS can be permanent (PTS), in which case the loss of hearing sensitivity is not fully recoverable, or temporary (TTS), in which case the animal's hearing threshold would recover over time (Southall

et al.,

2007). Repeated sound exposure that leads to TTS could cause PTS. In severe cases of PTS, there can be total or partial deafness, while in most cases the animal has an impaired ability to hear sounds in specific frequency ranges (Kryter, 1985).

When PTS occurs, there is physical damage to the sound receptors in the ear (

i.e.,

tissue damage), whereas TTS represents primarily tissue fatigue and is reversible (Southall

et al.,

2007). In addition, other investigators have suggested that TTS is within the normal bounds of physiological variability and tolerance and does not represent physical injury (

e.g.,

Ward, 1997). Therefore, NMFS does not consider TTS to constitute auditory injury.

Relationships between TTS and PTS thresholds have not been studied in marine mammals, and there is no PTS data for cetaceans but such relationships are assumed to be similar to those in humans and other terrestrial mammals. PTS typically occurs at exposure levels at least several dBs above (a 40-dB threshold shift approximates PTS onset;

e.g.,

Kryter

et al.,

1966; Miller, 1974) that inducing mild TTS (a 6-dB threshold shift approximates TTS onset;

e.g.,

Southall

et al.

2007). Based on data from terrestrial mammals, a precautionary assumption is that the PTS thresholds for impulse sounds (such as airgun pulses as received close to the source) are at least 6 dB higher than the TTS threshold on a peak-pressure basis and PTS cumulative sound exposure level thresholds are 15 to 20 dB higher than TTS cumulative sound exposure level thresholds (Southall

et al.,

2007). Given the higher level of sound or longer exposure duration necessary to cause PTS as compared with TTS, it is considerably less likely that PTS could occur.

For mid-frequency cetaceans in particular, potential protective mechanisms may help limit onset of TTS or prevent onset of PTS. Such mechanisms include dampening of hearing, auditory adaptation, or behavioral amelioration (

e.g.,

Nachtigall and Supin, 2013; Miller

et al.,

2012; Finneran

et al.,

2015; Popov

et al.,

2016).

TTS is the mildest form of hearing impairment that can occur during exposure to sound (Kryter, 1985). While experiencing TTS, the hearing threshold rises, and a sound must be at a higher level in order to be heard. In terrestrial and marine mammals, TTS can last from minutes or hours to days (in cases of strong TTS). In many cases, hearing sensitivity recovers rapidly after exposure to the sound ends. Few data on sound levels and durations necessary to elicit mild TTS have been obtained for marine mammals.

Marine mammal hearing plays a critical role in communication with conspecifics, and interpretation of environmental cues for purposes such as predator avoidance and prey capture. Depending on the degree (elevation of threshold in dB), duration (

i.e.,

recovery time), and frequency range of TTS, and the context in which it is experienced, TTS can have effects on marine mammals ranging from discountable to serious. For example, a marine mammal may be able to readily compensate for a brief, relatively small amount of TTS in a non-critical frequency range that occurs during a time where ambient noise is lower and there are not as many competing sounds present. Alternatively, a larger amount and longer duration of TTS sustained during

time when communication is critical for successful mother/calf interactions could have more serious impacts.

Finneran

et al.

(2015) measured hearing thresholds in three captive bottlenose dolphins before and after exposure to ten pulses produced by a seismic airgun in order to study TTS induced after exposure to multiple pulses. Exposures began at relatively low levels and gradually increased over a period of several months, with the highest exposures at peak SPLs from 196 to 210 dB and cumulative (unweighted) SELs from 193-195 dB. No substantial TTS was observed. In addition, behavioral reactions were observed that indicated that animals can learn behaviors that effectively mitigate noise exposures (although exposure patterns must be learned, which is less likely in wild animals than for the captive animals considered in this study). The authors note that the failure to induce more significant auditory effects likely due to the intermittent nature of exposure, the relatively low peak pressure produced by the acoustic source, and the low-frequency energy in airgun pulses as compared with the frequency range of best sensitivity for dolphins and other mid-frequency cetaceans.

Currently, TTS data only exist for four species of cetaceans (bottlenose dolphin, beluga whale, harbor porpoise, and Yangtze finless porpoise) exposed to a limited number of sound sources (

i.e.,

mostly tones and octave-band noise) in laboratory settings (Finneran, 2015). In general, harbor porpoises have a lower TTS onset than other measured cetacean species (Finneran, 2015). Additionally, the existing marine mammal TTS data come from a limited number of individuals within these species. There are no data available on noise-induced hearing loss for mysticetes.

Critical questions remain regarding the rate of TTS growth and recovery after exposure to intermittent noise and the effects of single and multiple pulses. Data at present are also insufficient to construct generalized models for recovery and determine the time necessary to treat subsequent exposures as independent events. More information is needed on the relationship between auditory evoked potential and behavioral measures of TTS for various stimuli. For summaries of data on TTS in marine mammals or for further discussion of TTS onset thresholds, please see Southall

et al.

(2007, 2019), Finneran and Jenkins (2012), Finneran (2015), and NMFS (2018).

Behavioral Effects

—Behavioral disturbance may include a variety of effects, including subtle changes in behavior (

e.g.,

minor or brief avoidance of an area or changes in vocalizations), more conspicuous changes in similar behavioral activities, and more sustained and/or potentially severe reactions, such as displacement from or abandonment of high-quality habitat. Behavioral responses to sound are highly variable and context-specific and any reactions depend on numerous intrinsic and extrinsic factors (

e.g.,

species, state of maturity, experience, current activity, reproductive state, auditory sensitivity, time of day), as well as the interplay between factors (

e.g.,

Richardson

et al.,

1995; Wartzok

et al.,

2003; Southall

et al.,

2007, 2019; Weilgart, 2007; Archer

et al.,

2010). Behavioral reactions can vary not only among individuals but also within an individual, depending on previous experience with a sound source, context, and numerous other factors (Ellison

et al.,

2012), and can vary depending on characteristics associated with the sound source (

e.g.,

whether it is moving or stationary, number of sources, distance from the source). Please see Appendices B-C of Southall

et al.

(2007) for a review of studies involving marine mammal behavioral responses to sound.

Habituation can occur when an animal's response to a stimulus wanes with repeated exposure, usually in the absence of unpleasant associated events (Wartzok

et al.,

2003). Animals are most likely to habituate to sounds that are predictable and unvarying. It is important to note that habituation is appropriately considered as a “progressive reduction in response to stimuli that are perceived as neither aversive nor beneficial,” rather than as, more generally, moderation in response to human disturbance (Bejder

et al.,

2009). The opposite process is sensitization, when an unpleasant experience leads to subsequent responses, often in the form of avoidance, at a lower level of exposure. As noted, behavioral state may affect the type of response. For example, animals that are resting may show greater behavioral change in response to disturbing sound levels than animals that are highly motivated to remain in an area for feeding (Richardson

et al.,

1995; NRC, 2003; Wartzok

et al.,

2003). Controlled experiments with captive marine mammals have showed pronounced behavioral reactions, including avoidance of loud sound sources (Ridgway

et al.,

1997). Observed responses of wild marine mammals to loud pulsed sound sources (typically seismic airguns or acoustic harassment devices) have been varied but often consist of avoidance behavior or other behavioral changes suggesting discomfort (Morton and Symonds, 2002; see also Richardson

et al.,

1995; Nowacek

et al.,

2007). However, many delphinids approach acoustic source vessels with no apparent discomfort or obvious behavioral change (

e.g.,

Barkaszi

et al.,

2012).

Available studies show wide variation in response to underwater sound; therefore, it is difficult to predict specifically how any given sound in a particular instance might affect marine mammals perceiving the signal. If a marine mammal does react briefly to an underwater sound by changing its behavior or moving a small distance, the impacts of the change are unlikely to be significant to the individual, let alone the stock or population. However, if a sound source displaces marine mammals from an important feeding or breeding area for a prolonged period, impacts on individuals and populations could be significant (

e.g.,

Lusseau and Bejder, 2007; Weilgart, 2007; NRC, 2005). However, there are broad categories of potential response, which we describe in greater detail here, that include alteration of dive behavior, alteration of foraging behavior, effects to breathing, interference with or alteration of vocalization, avoidance, and flight.

Changes in dive behavior can vary widely, and may consist of increased or decreased dive times and surface intervals as well as changes in the rates of ascent and descent during a dive (

e.g.,

Frankel and Clark, 2000; Ng and Leung, 2003; Nowacek

et al.,

2004; Goldbogen

et al.,

2013a, b). Variations in dive behavior may reflect interruptions in biologically significant activities (

e.g.,

foraging) or they may be of little biological significance. The impact of an alteration to dive behavior resulting from an acoustic exposure depends on what the animal is doing at the time of the exposure and the type and magnitude of the response.

Disruption of feeding behavior can be difficult to correlate with anthropogenic sound exposure, so it is usually inferred by observed displacement from known foraging areas, the appearance of secondary indicators (

e.g.,

bubble nets or sediment plumes), or changes in dive behavior. As for other types of behavioral response, the frequency, duration, and temporal pattern of signal presentation, as well as differences in species sensitivity, are likely contributing factors to differences in response in any given circumstance (

e.g.,

Croll

et al.,

2001; Nowacek

et al.;

2004; Madsen

et al.,

2006; Yazvenko

et al.,

2007). A determination of whether foraging disruptions incur fitness consequences would require information on or estimates of the energetic requirements of the affected individuals and the relationship between prey availability, foraging effort and success, and the life history stage of the animal.

Visual tracking, passive acoustic monitoring, and movement recording tags were used to quantify sperm whale behavior prior to, during, and following exposure to airgun arrays at received levels in the range 140-160 dB at distances of 7-13 km, following a phase-in of sound intensity and full array exposures at 1-13 km (Madsen

et al.,

2006; Miller

et al.,

2009). Sperm whales did not exhibit horizontal avoidance behavior at the surface. However, foraging behavior may have been affected. The sperm whales exhibited 19 percent less vocal (buzz) rate during full exposure relative to post exposure, and the whale that was approached most closely had an extended resting period and did not resume foraging until the airguns had ceased firing. The remaining whales continued to execute foraging dives throughout exposure; however, swimming movements during foraging dives were 6 percent lower during exposure than control periods (Miller

et al.,

2009). These data raise concerns that seismic surveys may impact foraging behavior in sperm whales, although more data are required to understand whether the differences were due to exposure or natural variation in sperm whale behavior (Miller

et al.,

2009).

Variations in respiration naturally vary with different behaviors and alterations to breathing rate as a function of acoustic exposure can be expected to co-occur with other behavioral reactions, such as a flight response or an alteration in diving. However, respiration rates in and of themselves may be representative of annoyance or an acute stress response. Various studies have shown that respiration rates may either be unaffected or could increase, depending on the species and signal characteristics, again highlighting the importance in understanding species differences in the tolerance of underwater noise when determining the potential for impacts resulting from anthropogenic sound exposure (

e.g.,

Kastelein

et al.,

2001, 2005, 2006; Gailey

et al.,

2007, 2016).

Marine mammals vocalize for different purposes and across multiple modes, such as whistling, echolocation click production, calling, and singing. Changes in vocalization behavior in response to anthropogenic noise can occur for any of these modes and may result from a need to compete with an increase in background noise or may reflect increased vigilance or a startle response. For example, in the presence of potentially masking signals, humpback whales and killer whales have been observed to increase the length of their songs or amplitude of calls (Miller

et al.,

2000; Fristrup

et al.,

2003; Foote

et al.,

2004; Holt

et al.,

2012), while right whales have been observed to shift the frequency content of their calls upward while reducing the rate of calling in areas of increased anthropogenic noise (Parks

et al.,

2007). In some cases, animals may cease sound production during production of aversive signals (Bowles

et al.,

1994).

Cerchio

et al.

(2014) used passive acoustic monitoring to document the presence of singing humpback whales off the coast of northern Angola and to opportunistically test for the effect of seismic survey activity on the number of singing whales. Two recording units were deployed between March and December 2008 in the offshore environment; numbers of singers were counted every hour. Generalized Additive Mixed Models were used to assess the effect of survey day (seasonality), hour (diel variation), moon phase, and received levels of noise (measured from a single pulse during each ten minute sampled period) on singer number. The number of singers significantly decreased with increasing received level of noise, suggesting that humpback whale breeding activity was disrupted to some extent by the survey activity.

Castellote

et al.

(2012) reported acoustic and behavioral changes by fin whales in response to shipping and airgun noise. Acoustic features of fin whale song notes recorded in the Mediterranean Sea and northeast Atlantic Ocean were compared for areas with different shipping noise levels and traffic intensities and during a seismic airgun survey. During the first 72 h of the survey, a steady decrease in song received levels and bearings to singers indicated that whales moved away from the acoustic source and out of the study area. This displacement persisted for a time period well beyond the 10-day duration of seismic airgun activity, providing evidence that fin whales may avoid an area for an extended period in the presence of increased noise. The authors hypothesize that fin whale acoustic communication is modified to compensate for increased background noise and that a sensitization process may play a role in the observed temporary displacement.

Seismic pulses at average received levels of 131 dB re 1 μPa

2

-s caused blue whales to increase call production (Di Iorio and Clark, 2010). In contrast, McDonald

et al.

(1995) tracked a blue whale with seafloor seismometers and reported that it stopped vocalizing and changed its travel direction at a range of 10 km from the acoustic source vessel (estimated received level 143 dB pk-pk). Blackwell

et al.

(2013) found that bowhead whale call rates dropped significantly at onset of airgun use at sites with a median distance of 41-45 km from the survey. Blackwell

et al.

(2015) expanded this analysis to show that whales actually increased calling rates as soon as airgun signals were detectable before ultimately decreasing calling rates at higher received levels (

i.e.,

10-minute SELcum of ~127 dB). Overall, these results suggest that bowhead whales may adjust their vocal output in an effort to compensate for noise before ceasing vocalization effort and ultimately deflecting from the acoustic source (Blackwell

et al.,

2013, 2015). These studies demonstrate that even low levels of noise received far from the source can induce changes in vocalization and/or behavior for mysticetes.

Avoidance is the displacement of an individual from an area or migration path as a result of the presence of a sound or other stressors, and is one of the most obvious manifestations of disturbance in marine mammals (Richardson

et al.,

1995). For example, gray whales are known to change direction—deflecting from customary migratory paths—in order to avoid noise from seismic surveys (Malme

et al.,

1984). Humpback whales showed avoidance behavior in the presence of an active seismic array during observational studies and controlled exposure experiments in western Australia (McCauley

et al.,

2000). Avoidance may be short-term, with animals returning to the area once the noise has ceased (

e.g.,

Bowles

et al.,

1994; Goold, 1996; Stone

et al.,

2000; Morton and Symonds, 2002; Gailey

et al.,

2007). Longer-term displacement is possible, however, which may lead to changes in abundance or distribution patterns of the affected species in the affected region if habituation to the presence of the sound does not occur (

e.g.,

Bejder

et al.,

2006; Teilmann

et al.,

2006).

Forney

et al.

(2017) detail the potential effects of noise on marine mammal populations with high site fidelity, including displacement and auditory masking, noting that a lack of observed response does not imply absence of fitness costs and that

apparent tolerance of disturbance may have population-level impacts that are less obvious and difficult to document. As we discuss in describing our proposed mitigation later in this document, avoidance of overlap between disturbing noise and areas and/or times of particular importance for sensitive species may be critical to avoiding population-level impacts because (particularly for animals with high site fidelity) there may be a strong motivation to remain in the area despite negative impacts. Forney

et al.

(2017) state that, for these animals, remaining in a disturbed area may reflect a lack of alternatives rather than a lack of effects. The authors discuss several case studies, including western Pacific gray whales, which are a small population of mysticetes believed to be adversely affected by oil and gas development off Sakhalin Island, Russia (Weller

et al.,

2002; Reeves

et al.,

2005). Western gray whales display a high degree of interannual site fidelity to the area for foraging purposes, and observations in the area during airgun surveys has shown the potential for harm caused by displacement from such an important area (Weller

et al.,

2006; Johnson

et al.,

2007). Forney

et al.

(2017) also discuss beaked whales, noting that anthropogenic effects in areas where they are resident could cause severe biological consequences, in part because displacement may adversely affect foraging rates, reproduction, or health, while an overriding instinct to remain could lead to more severe acute effects.

A flight response is a dramatic change in normal movement to a directed and rapid movement away from the perceived location of a sound source. The flight response differs from other avoidance responses in the intensity of the response (

e.g.,

directed movement, rate of travel). Relatively little information on flight responses of marine mammals to anthropogenic signals exist, although observations of flight responses to the presence of predators have occurred (Connor and Heithaus, 1996). The result of a flight response could range from brief, temporary exertion and displacement from the area where the signal provokes flight to, in extreme cases, marine mammal strandings (Evans and England, 2001). However, it should be noted that response

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